Reland "Enable init_stack_vars for non-official Windows builds"

This is a reland of 4c424ef5

Windows bot is fixed with crrev.com/c/1946985

Original change's description:
> Enable init_stack_vars for non-official Windows builds
>
> With crrev.com/c/1914359 merged so we can enable the flag on Windows.
> Patch is similar to crrev.com/c/1795632 and crrev.com/c/1838383.
>
> Bug: 977230
> Change-Id: I166392ee0f65ed7fd7f68cbdd5b7a3b7d589539b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1854805
> Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
> Auto-Submit: Vitaly Buka <vitalybuka@chromium.org>
> Reviewed-by: Hans Wennborg <hans@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#719737}

Bug: 977230
Change-Id: I7fa02038503e83eb5ccdbba8c07dc08010c2722f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1941278Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720912}

build/config/compiler/BUILD.gn

@@ -143,11 +143,10 @@ declare_args() {
   # rest with 0xAA. This makes behavior of uninitialized memory bugs consistent,
   # recognizeble in debugger, and crashes memory accesses by uninitialized
   # pointers.
-  # TODO(vitalybuka): is_win needs next llvm roll.
+  # TODO(vitalybuka):
   # 'is_android' breaks content_shell_test_apk on android-kitkat-arm-rel.
   # 'use_xcode_clang' may call old clang.
-  init_stack_vars =
-      !is_android && !is_win && !use_xcode_clang && !is_official_build
+  init_stack_vars = !is_android && !use_xcode_clang && !is_official_build
 }
 
 declare_args() {