Fix blink_perf.canvas failure on chromium.perf

PerformanceTests/Canvas/upload-webgl-to-texture.html

Index: PerformanceTests/Canvas/upload-webgl-to-texture.html
diff --git a/PerformanceTests/Canvas/upload-webgl-to-texture.html b/PerformanceTests/Canvas/upload-webgl-to-texture.html
index e8781edcce0d1230cdf93df0651c57d1709e38f0..45b9c39aa33444eec734c2cf4221f0921ef5c0a8 100644
--- a/PerformanceTests/Canvas/upload-webgl-to-texture.html
+++ b/PerformanceTests/Canvas/upload-webgl-to-texture.html
@@ -6,9 +6,9 @@
 <script>
 
 var sourceCanvas3D = document.createElement('canvas');
-var sourceCtx = sourceCanvas3D.getContext('experimental-webgl');
+var sourceCtx = sourceCanvas3D.getContext('webgl');
 var destCanvas3D = document.createElement('canvas');
-var destCtx = destCanvas3D.getContext('experimental-webgl');
+var destCtx = destCanvas3D.getContext('webgl');
 if (!sourceCtx || !destCtx)
     CanvasRunner.logFatalError("\nWebGL is not supported or enabled on this platform!\n");
 var tex = null;