Functions annotated with @nosideeffects are not removed when it is aliased

In the below example, `Object.getOwnPropertyDescriptor` is annotated with `@nosideeffects` in `es5.js`, but its calls are not removed.

[closure-compiler-debugger](https://closure-compiler-debugger.appspot.com/#input0%3Dlet%2520a%2520%253D%2520Object.getOwnPropertyDescriptor%253B%250A%250Alet%2520b%2520%253D%2520Object.getOwnPropertyDescriptor(Object.prototype%252C%2520'hasOwnProperty')%253B%250A%250Alet%2520c%2520%253D%2520a(Object.prototype%252C'__proto__').get%253B%26input1%26conformanceConfig%26externs%26refasterjs-template%26includeDefaultExterns%3Dtrue%26CHECK_TYPES%3Dtrue%26REWRITE_MODULES_BEFORE_TYPECHECKING%3Dtrue%26ALIAS_ALL_STRINGS%3Dtrue%26AMBIGUATE_PROPERTIES%3Dtrue%26COALESCE_VARIABLE_NAMES%3Dtrue%26COLLAPSE_VARIABLE_DECLARATIONS%3Dtrue%26COLLAPSE_ANONYMOUS_FUNCTIONS%3Dtrue%26COLLAPSE_PROPERTIES%3Dtrue%26COLLAPSE_OBJECT_LITERALS%3Dtrue%26COMPUTE_FUNCTION_SIDE_EFFECTS%3Dtrue%26CONVERT_TO_DOTTED_PROPERTIES%3Dtrue%26CROSS_CHUNK_CODE_MOTION%3Dtrue%26CROSS_CHUNK_METHOD_MOTION%3Dtrue%26DEAD_ASSIGNMENT_ELIMINATION%3Dtrue%26DEVIRTUALIZE_METHODS%3Dtrue%26DISAMBIGUATE_PROPERTIES%3Dtrue%26EXTRACT_PROTOTYPE_MEMBER_DECLARATIONS%3Dtrue%26FOLD_CONSTANTS%3Dtrue%26INLINE_CONSTANTS%3Dtrue%26INLINE_FUNCTIONS%3Dtrue%26INLINE_PROPERTIES%3Dtrue%26INLINE_VARIABLES%3Dtrue%26LABEL_RENAMING%3Dtrue%26OPTIMIZE_CALLS%3Dtrue%26OPTIMIZE_CONSTRUCTORS%3Dtrue%26OPTIMIZE_ARGUMENTS_ARRAY%3Dtrue%26REMOVE_ABSTRACT_METHODS%3Dtrue%26REMOVE_DEAD_CODE%3Dtrue%26REMOVE_UNUSED_CLASS_PROPERTIES%3Dtrue%26REMOVE_UNUSED_PROTOTYPE_PROPERTIES%3Dtrue%26REMOVE_UNUSED_VARIABLES%3Dtrue%26REWRITE_FUNCTION_EXPRESSIONS%3Dtrue%26SMART_NAME_REMOVAL%3Dtrue%26USE_TYPES_FOR_LOCAL_OPTIMIZATION%3Dtrue%26VARIABLE_RENAMING%3Dtrue%26PROPERTY_RENAMING%3Dtrue%26MOVE_FUNCTION_DECLARATIONS%3Dtrue%26SYNTHETIC_BLOCK_MARKER%3Dtrue%26CLOSURE_PASS%3Dtrue%26PRESERVE_TYPE_ANNOTATIONS%3Dtrue%26PRETTY_PRINT%3Dtrue)

```js
let a = Object.getOwnPropertyDescriptor;
let b = Object.getOwnPropertyDescriptor(Object.prototype, 'hasOwnProperty');
let c = a(Object.prototype,'__proto__').get;
```

```js
'use strict'; var a = Object.getOwnPropertyDescriptor; Object.getOwnPropertyDescriptor(Object.prototype, "hasOwnProperty"); a(Object.prototype, "__proto__");
```

Originally from https://groups.google.com/g/closure-compiler-discuss/c/1ibhiOqVzHo/m/Y5TIDPbpAQAJ.