heap mismatch due to VS2015 aliasing to delete[] a function that calls delete

While investigating #1870, running outside of the chrome_tests script, content_unittests FileSystemDirURLRequestJobTest.DirectoryListing (and probably any other test) has this mismatch reported:

```
[==========] 1 test from 1 test case ran. (3714 ms total)
[ PASSED ] 1 test.
~~Dr.M~~
~~Dr.M~~ Error #1: INVALID HEAP ARGUMENT: allocated with operator new, freed with operator delete[]
~~Dr.M~~ # 0 drmemorylib.dll!replace_operator_delete_array [d:\derek\drmemory\git\src\common\alloc_replace.c:2998]
~~Dr.M~~ # 1 v8.dll!v8::internal::DateCache::`scalar deleting destructor'
~~Dr.M~~ # 2 v8.dll!v8::internal::Isolate::~Isolate [z:\derek\chromium\src\v8\src\isolate.cc:2016]
~~Dr.M~~ # 3 v8.dll!v8::internal::Isolate::TearDown [z:\derek\chromium\src\v8\src\isolate.cc:1908]
~~Dr.M~~ # 4 webcore_shared.dll!blink::V8PerIsolateData::~V8PerIsolateData [z:\derek\chromium\src\third_party\webkit\source\bindings\core\v8\v8perisolatedata.cpp:151]
~~Dr.M~~ # 5 webcore_shared.dll!blink::V8Initializer::shutdownMainThread [z:\derek\chromium\src\third_party\webkit\source\bindings\core\v8\v8initializer.cpp:398]
~~Dr.M~~ # 6 content::UnitTestTestSuite::~UnitTestTestSuite [z:\derek\chromium\src\content\public\test\unittest_test_suite.cc:45]
~~Dr.M~~ # 7 __scrt_common_main_seh [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
~~Dr.M~~ # 8 KERNEL32.dll!BaseThreadInitThunk
~~Dr.M~~ Note: @0:00:30.576 in thread 3700
~~Dr.M~~ Note: memory was allocated here:
~~Dr.M~~ Note: # 0 drmemorylib.dll!replace_operator_new [d:\derek\drmemory\git\src\common\alloc_replace.c:2899]
~~Dr.M~~ Note: # 1 v8.dll!v8::base::OS::CreateTimezoneCache [z:\derek\chromium\src\v8\src\base\platform\platform-win32.cc:454]
~~Dr.M~~ Note: # 2 v8.dll!v8::internal::Snapshot::Initialize [z:\derek\chromium\src\v8\src\snapshot\snapshot-common.cc:61]
~~Dr.M~~ Note: # 3 v8.dll!v8::Isolate::New [z:\derek\chromium\src\v8\src\api.cc:7277]
~~Dr.M~~ Note: # 4 gin.dll!gin::IsolateHolder::IsolateHolder [z:\derek\chromium\src\gin\isolate_holder.cc:41]
~~Dr.M~~ Note: # 5 gin.dll!gin::IsolateHolder::IsolateHolder [z:\derek\chromium\src\gin\isolate_holder.cc:28]
~~Dr.M~~ Note: # 6 content::TestBlinkWebUnitTestSupport::TestBlinkWebUnitTestSupport [z:\derek\chromium\src\content\test\test_blink_web_unit_test_support.cc:121]
~~Dr.M~~ Note: # 7 content::UnitTestTestSuite::UnitTestTestSuite [z:\derek\chromium\src\content\public\test\unittest_test_suite.cc:39]
~~Dr.M~~ Note: # 8 main [z:\derek\chromium\src\content\test\run_all_unittests.cc:26]
```

Relevant source code:

```
return new TimezoneCache();

delete date_cache_;

void OS::DisposeTimezoneCache(TimezoneCache* cache) {
delete cache;
}
```

Analysis:

```
% grep delete logs/symcache/v8.dll.txt
operator delete,0x10db3b
operator delete[] nothrow,0x0
operator delete[],0x10afb0
operator delete nothrow,0x0

0:000> x v8!operator delete*
6565f11d v8!operator delete (void *, unsigned int)
6565db3b v8!operator delete (void *)
6565afb0 v8!operator delete[] (void *)

intercepting operator delete @0x6565db3b type 12 in module v8.dll
intercepting operator delete[] @0x6565afb0 type 13 in module v8.dll

in event_basic_block(tag=0x6566f84c)
in event_basic_block(tag=0x6566fd70)
set range 0x003af990-0x003af994 => 0x0
replace_operator_delete_array 0x043b8c90
replace_operator_delete 0x043b8c90
addr_is_debug_delete: 0x6566fd82 => v8::internal::DateCache::
addr_is_debug_delete: 0x6565db3b => operator delete

Error #1: INVALID HEAP ARGUMENT: allocated with operator new, freed with operator delete[]
#0 drmemorylib.dll!replace_operator_delete_array [d:\derek\drmemory\git\src\common\alloc_replace.c:2998] (0x73964130 ) modid:117
#1 v8.dll!v8::internal::DateCache::`scalar deleting destructor' (0x6566fd87 ) modid:57
#2 v8.dll!v8::internal::Isolate::~Isolate [z:\derek\chromium\src\v8\src\isolate.cc:2016] (0x6566f852 ) modid:57

v8!v8::internal::DateCache::`scalar deleting destructor':
6566fd70 55 push ebp
6566fd71 8bec mov ebp,esp
6566fd73 56 push esi
6566fd74 8bf1 mov esi,ecx
6566fd76 ffb62c020000 push dword ptr [esi+22Ch]
6566fd7c c70648039e65 mov dword ptr [esi],offset v8!v8::internal::DateCache::`vftable' (659e0348)
6566fd82 e829b2feff call v8!v8::base::OS::DisposeTimezoneCache (6565afb0)
6566fd87

v8!v8::base::OS::DisposeTimezoneCache [z:\derek\chromium\src\v8\src\base\platform\platform-win32.cc @ 458]:
6565afb0 e9862b0000 jmp v8!operator delete (6565db3b)

v8!operator delete [f:\dd\vctools\crt\vcstartup\src\heap\delete_scalar.cpp @ 15]:
6565db3b e998160000 jmp v8!free (6565f1d8)
```

So v8::base::OS::DisposeTimezoneCache == operator delete[]. This is hard to solve, b/c here we have separate delete and delete[] and it looks at the surface like we can successfully detect mismatches. How can we possibly know that the compiler is going to place DisposeTimezoneCache where delete[] is instead of delete? In some sense it seems like a bug, though with no regular consequences.

This will not show up on Cr bots b/c we run with -no_check_delete_mismatch for Release build.
That was due to another related issue in v8: #1625.

For non-Cr DrMem: it is not clear what we can do other than suggest that heap mismatch only be enabled for non-VS-optimized builds or something.

This just adds more nails in the coffin of the whole delete vs delete[] mismatch detection feature with Visual Studio: the compiler's lack of concern for operator separation makes it impractical.