Enable WGSL support by default

Explictly turned off for Skia, since it does not yet have Tint in its DEPS.

Roll third_party/tint/ e8c12f32f..c5cd8f5bd (3 commits)

https://dawn.googlesource.com/tint/+log/e8c12f32f9a9..c5cd8f5bd382

$ git log e8c12f32f..c5cd8f5bd --date=short --no-merges --format='%ad %ae %s'
2020-07-28 rharrison Remove binutils from DEPS and pull in changes to build.gni from Dawn
2020-07-28 rharrison Get 'gn gen --check' passing
2020-07-28 idanr Fix Tint ninja build

Created with:
  roll-dep third_party/tint

BUG=tint:123

Change-Id: Icd26c2d1b7329c94afa6f23c5c057de8efaee3e8
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/25523
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

DEPS

@@ -90,7 +90,7 @@ deps = {
 
   # WGSL support
   'third_party/tint': {
-    'url': '{dawn_git}/tint@e8c12f32f9a9517100f819f5bce35ad8d6e0bc78',
+    'url': '{dawn_git}/tint@c5cd8f5bd3823c7e4b0d1d26d5de3465a9159eec',
     'condition': 'dawn_standalone',
   },
 

scripts/dawn_features.gni

@@ -69,9 +69,9 @@ declare_args() {
   # Whether Dawn should enable X11 support.
   dawn_use_x11 = is_linux && !is_chromeos
 
-  # Enable support WGSL for shaders. Currently this is
-  # experimental, and requires dawn_tint_dir to be set.
-  dawn_enable_wgsl = false
+  # Enable support WGSL for shaders.
+  # Turned off for Skia, because Tint is currently not part of its DEPS.
+  dawn_enable_wgsl = !defined(is_skia_standalone)
 }
 
 # GN does not allow reading a variable defined in the same declare_args().