Internal functions can capture implementation names by using $jscomp$

Input for `SIMPLE_OPTIMIZATIONS`:

```
function u_0(){ while (i_1){ i_1() };function i_1(i_1$jscomp$1, i_1){ } }
```

Error output:

```
Exception in thread "main" java.lang.RuntimeException: INTERNAL COMPILER ERROR.
Please report this problem.

Multiple entries with same key: i_1$jscomp$1=VOID 1 [length: 5] [source_file: id_000004.input] and i_1$jscomp$1=VOID 1 [length: 5] [source_file: id_000004.input]
Node(CALL): id_000004.input:1:29
function u_0(){ while (i_1){ i_1() };function i_1(i_1$jscomp$1, i_1){ } }
Parent(EXPR_RESULT): id_000004.input:1:29
function u_0(){ while (i_1){ i_1() };function i_1(i_1$jscomp$1, i_1){ } }

at com.google.common.collect.ImmutableMap.conflictException(ImmutableMap.java:215)
at com.google.common.collect.ImmutableMap.checkNoConflict(ImmutableMap.java:209)
at com.google.common.collect.RegularImmutableMap.checkNoConflictInKeyBucket(RegularImmutableMap.java:147)
at com.google.common.collect.RegularImmutableMap.fromEntryArray(RegularImmutableMap.java:110)
at com.google.common.collect.ImmutableMap$Builder.build(ImmutableMap.java:393)
at com.google.javascript.jscomp.FunctionArgumentInjector.getFunctionCallParameterMap(FunctionArgumentInjector.java:176)
at com.google.javascript.jscomp.FunctionInjector.canInlineReferenceDirectly(FunctionInjector.java:935)
at com.google.javascript.jscomp.FunctionInjector.canInlineReferenceToFunction(FunctionInjector.java:314)
at com.google.javascript.jscomp.InlineFunctions$FindCandidatesReferences.maybeAddReferenceUsingMode(InlineFunctions.java:550)
at com.google.javascript.jscomp.InlineFunctions$FindCandidatesReferences.maybeAddReference(InlineFunctions.java:519)
at com.google.javascript.jscomp.InlineFunctions$FindCandidatesReferences.visitCallSite(InlineFunctions.java:508)
at com.google.javascript.jscomp.InlineFunctions$CallVisitor.visit(InlineFunctions.java:445)
at com.google.javascript.jscomp.InlineFunctions$FindCandidatesReferences.visit(InlineFunctions.java:500)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:909)
at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:1037)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:905)
at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:1037)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:902)
at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:1037)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:902)
at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:1037)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:902)
at com.google.javascript.jscomp.NodeTraversal.traverseFunction(NodeTraversal.java:948)
at com.google.javascript.jscomp.NodeTraversal.handleFunction(NodeTraversal.java:854)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:880)
at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:1037)
at com.google.javascript.jscomp.NodeTraversal.handleScript(NodeTraversal.java:842)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:877)
at com.google.javascript.jscomp.NodeTraversal.traverseChildren(NodeTraversal.java:1037)
at com.google.javascript.jscomp.NodeTraversal.traverseBranch(NodeTraversal.java:905)
at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:415)
at com.google.javascript.jscomp.NodeTraversal.traverse(NodeTraversal.java:425)
at com.google.javascript.jscomp.InlineFunctions.process(InlineFunctions.java:130)
at com.google.javascript.jscomp.PhaseOptimizer$NamedPass.process(PhaseOptimizer.java:317)
at com.google.javascript.jscomp.PhaseOptimizer$Loop.process(PhaseOptimizer.java:462)
at com.google.javascript.jscomp.PhaseOptimizer.process(PhaseOptimizer.java:232)
at com.google.javascript.jscomp.Compiler.performOptimizations(Compiler.java:2417)
at com.google.javascript.jscomp.Compiler.lambda$stage2Passes$1(Compiler.java:802)
at com.google.javascript.jscomp.CompilerExecutor.runInCompilerThread(CompilerExecutor.java:129)
at com.google.javascript.jscomp.Compiler.runInCompilerThread(Compiler.java:829)
at com.google.javascript.jscomp.Compiler.stage2Passes(Compiler.java:799)
at com.google.javascript.jscomp.Compiler.compile(Compiler.java:689)
at com.google.javascript.jscomp.Compiler.compile(Compiler.java:656)
at edu.berkeley.cs.jqf.examples.closure.CompilerTest.main(CompilerTest.java:68)
Caused by: java.lang.IllegalArgumentException: Multiple entries with same key: i_1$jscomp$1=VOID 1 [length: 5] [source_file: id_000004.input] and i_1$jscomp$1=VOID 1 [length: 5] [source_file: id_000004.input]
... 44 more

```

Affects: v20200405

Reproduce by passing a file with the input to this class:
```
import com.google.javascript.jscomp.CompilationLevel;
import com.google.javascript.jscomp.CompilerOptions;
import com.google.javascript.jscomp.Result;
import com.google.javascript.jscomp.SourceFile;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;

import static org.junit.Assume.assumeTrue;

public class Compiler {

static {
java.util.logging.LogManager.getLogManager().reset();
}

// Compiler, options, and predefined JS environment
private com.google.javascript.jscomp.Compiler compiler = new com.google.javascript.jscomp.Compiler(new PrintStream(new ByteArrayOutputStream(), false));
private CompilerOptions options = new CompilerOptions();
private SourceFile externs = SourceFile.fromCode("externs", "");

public void initCompiler() {
// Don't use threads
compiler.disableThreads();
// Don't print things
options.setPrintConfig(false);
// Enable all safe optimizations
CompilationLevel.SIMPLE_OPTIMIZATIONS.setOptionsForCompilationLevel(options);
}

/** Compiles an input and returns its result */
private Result compile(SourceFile input) {
return compiler.compile(externs, input, options);
}

public static void main(String[] args) {
Compiler t = new Compiler();
t.compiler = new com.google.javascript.jscomp.Compiler(System.out);
t.initCompiler();
t.compiler.compile(t.externs, SourceFile.fromFile(args[0]), t.options);
}
}
```

Compiler options (default options):
```
aggressiveFusion=false
aliasableStrings=[]
aliasAllStrings=false
aliasHandler=com.google.javascript.jscomp.CompilerOptions$NullAliasTransformationHandler@5bb21b69
aliasStringsBlacklist=
allowHotswapReplaceScript=false
ambiguateProperties=false
angularPass=false
anonymousFunctionNaming=OFF
assumeClosuresOnlyCaptureReferences=false
assumeGettersArePure=true
assumeStrictThis=false
browserResolverPrefixReplacements={}
brokenClosureRequiresLevel=ERROR
checkDeterminism=false
checkGlobalNamesLevel=OFF
checkGlobalThisLevel=OFF
checkMissingGetCssNameLevel=OFF
checksOnly=false
checkSuspiciousCode=false
checkSymbols=false
checkTypes=false
closurePass=true
coalesceVariableNames=true
collapseAnonymousFunctions=false
collapseObjectLiterals=true
collapseProperties=NONE
collapseVariableDeclarations=true
colorizeErrorOutput=false
computeFunctionSideEffects=false
conformanceConfigs=[]
conformanceRemoveRegexFromPath=Optional.of(^((.*/)?google3/)?((^/)?(blaze|bazel)-out/[^/]+/bin/)?)
continueAfterErrors=false
convertToDottedProperties=true
crossChunkCodeMotion=false
crossChunkCodeMotionNoStubMethods=false
crossChunkMethodMotion=false
dartPass=false
deadAssignmentElimination=true
declaredGlobalExternsOnWindow=true
defineReplacements={}
dependencyOptions=DependencyOptions{mode=SORT_ONLY
entryPoints=[]}
devirtualizeMethods=false
devMode=OFF
disambiguatePrivateProperties=false
disambiguateProperties=false
enableModuleRewriting=true
enforceAccessControlCodingConventions=false
environment=BROWSER
errorFormat=SINGLELINE
es6ModuleTranspilation=COMPILE
exportLocalPropertyDefinitions=false
exportTestFunctions=false
externExports=false
extractPrototypeMemberDeclarations=OFF
extraSmartNameRemoval=false
filesToPrintAfterEachPassRegexList=[]
flowSensitiveInlineVariables=false
foldConstants=true
forceLibraryInjection=[]
gatherCssNames=false
generateExports=false
generatePseudoNames=false
generateTypedExterns=false
idGenerators={}
incrementalCheckMode=OFF
inferConsts=true
inferTypes=false
inlineConstantVars=false
inlineFunctionsLevel=LOCAL_ONLY
inlineGetters=false
inlineLocalVariables=true
inlineProperties=false
inlineVariables=false
inputDelimiter=// Input %num%
inputSourceMaps={}
instrumentForCoverage=false
instrumentForCoverageOnly=false
instrumentBranchCoverage=false
isolatePolyfills=false
j2clMinifierEnabled=true
j2clPassMode=AUTO
labelRenaming=true
languageIn=ECMASCRIPT_2019
languageOutIsDefaultStrict=Optional.absent()
legacyCodeCompile=false
lineBreak=false
lineLengthThreshold=500
markAsCompiled=false
maxFunctionSizeAfterInlining=-1
moduleRoots=[./]
chunksToPrintAfterEachPassRegexList=[]
moveFunctionDeclarations=false
nameGenerator=com.google.javascript.jscomp.DefaultNameGenerator@32464a14
optimizeArgumentsArray=true
optimizeCalls=false
outputFeatureSet=Optional.absent()
outputJs=NORMAL
outputJsStringUsage=false
parentChunkCanSeeSymbolsDeclaredInChildren=false
parseJsDocDocumentation=TYPES_ONLY
pathEscaper=ESCAPE
polymerExportPolicy=LEGACY
preferLineBreakAtEndOfFile=false
preferSingleQuotes=false
preferStableNames=false
preserveDetailedSourceInfo=false
preserveGoogProvidesAndRequires=false
preserveTypeAnnotations=false
prettyPrint=false
preventLibraryInjection=false
printConfig=true
printInputDelimiter=false
printSourceAfterEachPass=false
processCommonJSModules=false
propertyInvalidationErrors={}
propertyRenaming=OFF
protectHiddenSideEffects=true
quoteKeywordProperties=false
removeAbstractMethods=false
removeClosureAsserts=false
removeJ2clAsserts=true
removeDeadCode=true
removeUnusedClassProperties=false
removeUnusedConstructorProperties=false
removeUnusedLocalVars=true
removeUnusedPrototypeProperties=false
removeUnusedPrototypePropertiesInExterns=false
removeUnusedVars=false
renamePrefixNamespaceAssumeCrossChunkNames=false
replaceIdGenerators=false
replaceMessagesWithChromeI18n=false
replaceStringsFunctionDescriptions=[]
replaceStringsPlaceholderToken=
replaceStringsReservedStrings=[]
reserveRawExports=false
rewriteFunctionExpressions=false
rewritePolyfills=false
runtimeTypeCheck=false
shadowVariables=true
rewriteModulesBeforeTypechecking=true
skipNonTranspilationPasses=false
smartNameRemoval=false
sourceMapDetailLevel=ALL
sourceMapFormat=DEFAULT
sourceMapLocationMappings=[]
stripNamePrefixes=[]
stripNameSuffixes=[]
stripTypePrefixes=[]
stripTypes=[]
summaryDetailLevel=1
tracer=OFF
transformAMDToCJSModules=false
trustedStrings=false
tweakProcessing=OFF
tweakReplacements={}
emitUseStrict=Optional.absent()
useTypesForLocalOptimization=false
variableRenaming=LOCAL
warningsGuard=DiagnosticGroup(OFF)
DiagnosticGroup(ERROR)
DiagnosticGroup(OFF)
com.google.javascript.jscomp.DiagnosticGroup@4e4aea35(OFF)
wrapGoogModulesForWhitespaceOnly=true
```