Remove the 10.0.17134 SDK requirement for building Chromium

Until recently Chrome required the 10.0.17134 SDK to build because it
needed declarations from that SDK and there was no more recent SDK. Now
there is a more recent (10.0.17763) SDK which can also build Chrome and
the 10.0.17134 requirement is annoying.

Removing the requirement for a specific version means that some new
Chromium developer might try building with an *older* version, but that
is unlikely, and they will hit errors and will then just need to install
the latest. That is better than forcing developers to install an old SDK
version.

Bug: 907300
Change-Id: Iad5a5bb1cdab944926df030cb1adb46ae0d55b56
Reviewed-on: https://chromium-review.googlesource.com/c/1345652Reviewed-by: Xi Cheng <chengx@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610141}

build/toolchain/win/setup_toolchain.py

@@ -149,9 +149,6 @@ def _LoadToolchainEnv(cpu, sdk_dir, target_store):
     # Store target must come before any SDK version declaration
     if (target_store):
       args.append(['store'])
-    # Chromium requires the 10.0.17134.0 SDK - previous versions don't have
-    # all of the required declarations.
-    args.append('10.0.17134.0')
     variables = _LoadEnvFromBat(args)
   return _ExtractImportantEnvironment(variables)