Deflake css3/filter/effect layout tests

third_party/WebKit/LayoutTests/css3/filters/effect-sepia-hw.html

Index: third_party/WebKit/LayoutTests/css3/filters/effect-sepia-hw.html
diff --git a/third_party/WebKit/LayoutTests/css3/filters/effect-sepia-hw.html b/third_party/WebKit/LayoutTests/css3/filters/effect-sepia-hw.html
index 33a9d717ed82e4ac396e1552cd272cbfb65bebde..b7034e0777be0b36ef87c710dabc00af38c46982 100644
--- a/third_party/WebKit/LayoutTests/css3/filters/effect-sepia-hw.html
+++ b/third_party/WebKit/LayoutTests/css3/filters/effect-sepia-hw.html
@@ -1,11 +1,18 @@
+<!-- This test uses a particular image size to avoid hitting flakiness in mesa texture sampling.  See http://crbug.com/621892 for more details. -->
 <style>
 img {
     transform:translateZ(0);
 }
+div {
+    width: 160px;
+    height: 90px;
+    overflow: hidden;
+    display: inline-block;
+}
 </style>
-<img style="filter: sepia(0)" src="resources/reference.png">
-<img style="filter: sepia(0.2)" src="resources/reference.png">
-<img style="filter: sepia(0.4)" src="resources/reference.png">
-<img style="filter: sepia(0.6)" src="resources/reference.png">
-<img style="filter: sepia(0.8)" src="resources/reference.png">
-<img style="filter: sepia(1.0)" src="resources/reference.png">
+<div><img style="filter: sepia(0)" src="resources/reference_square.png"></div>
+<div><img style="filter: sepia(0.2)" src="resources/reference_square.png"></div>
+<div><img style="filter: sepia(0.4)" src="resources/reference_square.png"></div>
+<div><img style="filter: sepia(0.6)" src="resources/reference_square.png"></div>
+<div><img style="filter: sepia(0.8)" src="resources/reference_square.png"></div>
+<div><img style="filter: sepia(1.0)" src="resources/reference_square.png"></div>