Revert "WIP Canvas 2D/WebGL context: s/lowLatency/desynchronized/"

This reverts commit 3fa9fd5b2eb09d461012c832db99273bb8c5a905.

Reason for revert: Suspect cause of failure in webkit_layout_tests:
* external/wpt/2dcontext/context-attributes/getContextAttributes.html
https://ci.chromium.org/p/chromium/builders/ci/Mac10.11%20Tests/35391

Original change's description:
> WIP Canvas 2D/WebGL context: s/lowLatency/desynchronized/
>
> This CL renames s/lowLatency/desynchronized/ on web-exposed parts
> (s/low_latency/desynchronized/ internally) following [1,2] PRs
> (issue [3]), and extends wpt getContextAttributes.html.
>
> [1] whatwg/html#4360
> [2] KhronosGroup/WebGL#2753
> [3] whatwg/html#4087
>
> Bug: 944199
> Change-Id: Ic9d7bd6165f9dc9536613dc63e77b86b8ec42f7f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1532920
> Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
> Commit-Queue: Miguel Casas <mcasas@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#643323}

TBR=mcasas@chromium.org,foolip@chromium.org

Change-Id: I47d31863f61a882424e06aec40e93e8bc3875849
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 944199
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1534473
Reviewed-by: Fabrice de Gans-Riberi <fdegans@chromium.org>
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#643430}

2dcontext/context-attributes/getContextAttributes.html

@@ -6,34 +6,22 @@
 var testScenarios = [
     {testDescription: "Test default context creation attributes",
         canvasContextAttributes: {},
-        expectedContextAttributes: {alpha : true, desynchronized: false}},
+        expectedContextAttributes: {alpha : true}},
     {testDescription: "Test context creation attributes alpha: true",
         canvasContextAttributes: {alpha: true},
         expectedContextAttributes: {alpha : true}},
     {testDescription: "Test context creation attributes alpha: false",
         canvasContextAttributes: {alpha: false},
         expectedContextAttributes: {alpha : false}},
-    {testDescription: "Test context creation attributes desynchronized: true",
-        canvasContextAttributes: {desynchronized: true},
-        expectedContextAttributes: {desynchronized : true}},
-    {testDescription: "Test context creation attributes desynchronized: false",
-        canvasContextAttributes: {desynchronized: false},
-        expectedContextAttributes: {desynchronized : false}},
 ];
 
 function runTestScenario(testScenario) {
     var t = test(function() {
         var canvas = document. createElement('canvas');
         var ctx = canvas.getContext('2d', testScenario.canvasContextAttributes);
         var contextAttributes = ctx.getContextAttributes();
-        if (testScenario.expectedContextAttributes.alpha !== undefined) {
-            assert_equals(contextAttributes.alpha,
-                testScenario.expectedContextAttributes.alpha);
-        }
-        if (testScenario.expectedContextAttributes.desynchronized !== undefined) {
-            assert_equals(contextAttributes.desynchronized,
-                testScenario.expectedContextAttributes.desynchronized);
-        }
+        assert_equals(contextAttributes.alpha,
+            testScenario.expectedContextAttributes.alpha);
     }, testScenario.testDescription);
 }