Add SK_IGNORE_MASK_FILTER_GLYPH_FIX for rebaseline.

This defines a build flag to suppress a change in Skia
(https://review.skia.org/126615) which will require rebaselining a number
of text shadows.

Change-Id: Idfeee0a582a084d4a50eb295d7ff1a479e867132
Reviewed-on: https://chromium-review.googlesource.com/1050466Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Ben Wagner <bungeman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556863}

skia/BUILD.gn

@@ -149,7 +149,10 @@ config("skia_library_config") {
   # TODO: remove after Skia shader relocation (https://skia-review.googlesource.com/c/17927)
   include_dirs += [ "//third_party/skia/src/effects/gradients" ]
 
-  defines = [ "SK_USE_SKCMS" ]
+  defines = [
+    "SK_USE_SKCMS",
+    "SK_IGNORE_MASK_FILTER_GLYPH_FIX",
+  ]
 
   if (!is_ios && !use_system_freetype) {
     defines += [ "SK_FREETYPE_MINIMUM_RUNTIME_VERSION=(((FREETYPE_MAJOR) * 0x01000000) | ((FREETYPE_MINOR) * 0x00010000) | ((FREETYPE_PATCH) * 0x00000100))" ]