mousewheel-scroll.html flaky test updated.

Bug: 865755
Change-Id: Ic24c1405392ba42810f516f375a3d304a81a88ed
Reviewed-on: https://chromium-review.googlesource.com/1169779
Commit-Queue: Sahel Sharify <sahel@chromium.org>
Reviewed-by: Philip Rogers <pdr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582175}

third_party/WebKit/LayoutTests/TestExpectations

@@ -4701,8 +4701,6 @@ crbug.com/864994 [ Mac ] external/wpt/encoding/legacy-mb-korean/euc-kr/euckr-dec
 
 crbug.com/865432 [ Linux ] external/wpt/workers/modules/dedicated-worker-import-blob-url.any.worker.html [ Timeout Pass ]
 
-crbug.com/865755 [ Debug ] virtual/threaded/fast/scroll-behavior/smooth-scroll/mousewheel-scroll.html [ Failure Pass ]
-
 skbug.com/8155 virtual/gpu-rasterization/images/jpeg-yuv-progressive-image.html [ Pass Failure ]
 skbug.com/8155 virtual/gpu-rasterization/images/rgb-png-with-cmyk-color-profile.html [ Pass Failure ]
 

third_party/WebKit/LayoutTests/fast/scroll-behavior/smooth-scroll/mousewheel-scroll.html

@@ -27,15 +27,19 @@
         SPEED_INSTANT);
 
     // 40px per tick.
-    await waitFor( () => {return document.scrollingElement.scrollTop == 40 &&
-        document.scrollingElement.scrollLeft == 40;});
+    await waitFor( () => {
+        return approx_equals(document.scrollingElement.scrollTop, 40, 2) &&
+            approx_equals(document.scrollingElement.scrollLeft, 40, 2);
+    });
 
     // Undo the last tick in each direction to reset the scroll state before
     // starting the second test.
     await smoothScroll(1 * px_per_tick, x, y, source, 'upleft',
         SPEED_INSTANT);
-    await waitFor( () => {return document.scrollingElement.scrollTop == 0 &&
-        document.scrollingElement.scrollLeft == 0;});
+    await waitFor( () => {
+        return approx_equals(document.scrollingElement.scrollTop, 0, 2) &&
+            approx_equals(document.scrollingElement.scrollLeft, 0, 2);
+    });
 
   }, "This test ensures that consecutive mouse wheel ticks diagonally " +
       "scroll to the right offset. The main purpose of this test is to " +
@@ -60,8 +64,10 @@
         SPEED_INSTANT);
 
     // 40px per tick.
-    await waitFor( () => {return document.scrollingElement.scrollTop == 80 &&
-        document.scrollingElement.scrollLeft == 80;});
+    await waitFor( () => {
+        return approx_equals(document.scrollingElement.scrollTop, 80, 4) &&
+            approx_equals(document.scrollingElement.scrollLeft, 80, 4);
+    });
   }, "This test ensures that consecutive mouse wheel ticks vertically or " +
       "horizontally scroll to the right offset. The main purpose of this " +
       "test is to ensure that smooth scrolling on the compositor works as " +