Use kText, not kWindowFrameText for Canvastext on MacOS.

kWindowFrameText is not opaque (alpha < 1) and is not web compatible
with the initial value for the color property being Canvastext.

This matches what Safari does for Text and presumably will do for
Canvastext.

Bug: 1047472
Change-Id: Ibc14db48c730e109f5fea9e86f08e0075a69bcb0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2030957
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Reviewed-by: Alison Maher <almaher@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#738119}

third_party/blink/renderer/core/layout/layout_theme_mac.mm

@@ -443,8 +443,9 @@ Color LayoutThemeMac::SystemColor(CSSValueID css_value_id,
     case CSSValueID::kWindowframe:
       return GetSystemColor(MacSystemColorID::kWindowFrame);
     case CSSValueID::kWindowtext:
-    case CSSValueID::kCanvastext:
       return GetSystemColor(MacSystemColorID::kWindowFrameText);
+    case CSSValueID::kCanvastext:
+      return GetSystemColor(MacSystemColorID::kText);
     default:
       break;
   }

third_party/blink/web_tests/TestExpectations

@@ -6444,9 +6444,6 @@ crbug.com/1047208 http/tests/serviceworker/update-served-from-cache.html [ Pass
 crbug.com/1047293 [ Mac ] editing/pasteboard/pasteboard_with_unfocused_selection.html [ Pass Failure ]
 crbug.com/1047420 [ Mac ] http/tests/devtools/persistence/persistence-move-breakpoints-on-reload.js [ Pass Failure ]
 
-# Color difference on MacOS 10.14
-crbug.com/1047126 [ Mac10.14 ] external/wpt/css/css-color/color-initial-canvastext.html [ Failure ]
-
 # Sheriff 2020-01-31
 crbug.com/1047760 [ Win ] http/tests/devtools/screen-orientation-override.js [ Pass Timeout ]