Revert "Reland "ARM64 capable toolchain hash""

This reverts commit 2a16f2ba.

Reason for revert: Strongly suspected as culprit for bug 919163: angle_deqp_gles2_d3d11_tests failing on chromium.gpu.fyi/Win7 FYI dEQP Release (AMD)

Original change's description:
> Reland "ARM64 capable toolchain hash"
> 
> This is a reland of dd8c7b26
> 
> Original change's description:
> > ARM64 capable toolchain hash
> >
> > This updates Chrome to build with a toolchain based on VS 2017 15.9.3
> > and the Windows 10.0.17763.132 SDK, with the ARM64 components included to
> > support building for ARM64 for Win32. This adds about 400 MB to the package
> > size, a bit less than a 50% increase.
> >
> > Packaging was done on a Windows Server 2016 VM, cleanly created for this
> > purpose.
> >
> > The package was created by downloading VS 2017 Update 9.3, from
> > https://www.visualstudio.com/vs/, and then running the installer like this:
> >
> > $ PATH_TO_INSTALLER.EXE ^
> >     --add Microsoft.VisualStudio.Workload.NativeDesktop ^
> >     --add Microsoft.VisualStudio.Component.VC.ATLMFC ^
> >     --add Microsoft.VisualStudio.Component.VC.Tools.ARM64 ^
> >     --add Microsoft.VisualStudio.Component.VC.MFC.ARM64 ^
> >     --includeRecommended --passive
> >
> > Then Add or Remove Programs was used to modify the SDK to add the
> > Debuggers package.
> >
> > Then the packaging script was run like this:
> >
> >   python depot_tools\win_toolchain\package_from_installed.py 2017 -w 10.0.17763.0
> >
> > This was tested on two VMs to ensure that the results are consistent.
> >
> > This should not significantly affect the x86 and x64 builds, although
> > there may have been some STL and CRT changes that could cause changes.
> >
> > Bug: 893460
> > Change-Id: I33dd5b915ffaf17f306d804f561d26bf82060b03
> > Reviewed-on: https://chromium-review.googlesource.com/c/1342814
> > Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> > Reviewed-by: Nico Weber <thakis@chromium.org>
> > Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#616123}
> 
> Bug: 893460,915046
> Change-Id: I1f4f8fb7f37785ba935ef698964fa87f9a91e313
> Reviewed-on: https://chromium-review.googlesource.com/c/1377510
> Reviewed-by: Dirk Pranke <dpranke@chromium.org>
> Reviewed-by: Nico Weber <thakis@chromium.org>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#620001}

TBR=thakis@chromium.org,dpranke@chromium.org,machenbach@chromium.org,brucedawson@chromium.org,scottmg@chromium.org

Change-Id: Ic032ab4307045ada9b2f6e0955bc4ad7dc8e84f8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 893460, 915046, 919163
Reviewed-on: https://chromium-review.googlesource.com/c/1396560Reviewed-by: Matthew Wolenetz <wolenetz@chromium.org>
Commit-Queue: Matthew Wolenetz <wolenetz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620030}

build/vs_toolchain.py

@@ -364,8 +364,9 @@ def _GetDesiredVsToolchainHashes():
   to build with."""
   env_version = GetVisualStudioVersion()
   if env_version == '2017':
-    # VS 2017 Update 9 (15.9.3) with 10.0.17763.132 SDK, with ARM64 libraries.
-    toolchain_hash = 'e04af53255fe13c130e9cfde7d9ac861b9fb674a'
+    # VS 2017 Update 7.1 (15.7.1) with 10.0.17134.12 SDK, rebuilt with
+    # dbghelp.dll fix.
+    toolchain_hash = '3bc0ec615cf20ee342f3bc29bc991b5ad66d8d2c'
     # Third parties that do not have access to the canonical toolchain can map
     # canonical toolchain version to their own toolchain versions.
     toolchain_hash_mapping_key = 'GYP_MSVS_HASH_%s' % toolchain_hash