Fixed WebglRenderingContextBase toImageData

third_party/WebKit/LayoutTests/virtual/threaded/fast/idleToBlob/OffscreenCanvas-convertToBlob-webgl-main-expected.html

 <img id="png"/>
-<script>
+<img id="jpeg-high"/>
+<img id="jpeg-low"/>
+<img id="webp-high"/>
+<img id="webp-low"/>
+<script type="text/javascript">
 if (window.testRunner) {
   testRunner.waitUntilDone();
 }
 
 var pngImage = document.getElementById('png');
+var jpegImageHigh = document.getElementById('jpeg-high');
+var jpegImageLow = document.getElementById('jpeg-low');
+var webpImageHigh = document.getElementById('webp-high');
+var webpImageLow = document.getElementById('webp-low');
+var numTestCount = 5;
 function imageLoaded() {
-  if (window.testRunner) {
+  numTestCount--;
+  if (numTestCount == 0 && window.testRunner) {
     window.testRunner.notifyDone();
   }
 }
 pngImage.addEventListener('load', imageLoaded);
+jpegImageHigh.addEventListener('load', imageLoaded);
+jpegImageLow.addEventListener('load', imageLoaded);
+webpImageHigh.addEventListener('load', imageLoaded);
+webpImageLow.addEventListener('load', imageLoaded);
 
 var canvas = document.createElement("canvas");
 canvas.width = 50;
 canvas.height = 50;
 var gl = canvas.getContext('webgl');
 gl.clearColor(0, 1, 0, 1);
 gl.clear(gl.COLOR_BUFFER_BIT);
 
 canvas.toBlob(function(blob) {
   pngImage.src = URL.createObjectURL(blob);
 });
+
+canvas.toBlob(function(blob) {
+  jpegImageHigh.src = URL.createObjectURL(blob);
+}, "image/jpeg", 1.0);
+
+canvas.toBlob(function(blob) {
+    jpegImageLow.src = URL.createObjectURL(blob);
+}, "image/jpeg", 0.2)
+
+canvas.toBlob(function(blob) {
+    webpImageHigh.src = URL.createObjectURL(blob);
+}, "image/webp", 1.0);
+
+canvas.toBlob(function(blob) {
+    webpImageLow.src = URL.createObjectURL(blob);
+}, "image/webp", 0.2);
+
 </script>