Add a partial load test for an animated GIF image

third_party/WebKit/LayoutTests/http/tests/images/gif-animated-partial-load.html

Index: third_party/WebKit/LayoutTests/http/tests/images/gif-animated-partial-load.html
diff --git a/third_party/WebKit/LayoutTests/http/tests/images/gif-animated-partial-load.html b/third_party/WebKit/LayoutTests/http/tests/images/gif-animated-partial-load.html
new file mode 100644
index 0000000000000000000000000000000000000000..5e8e125d3061d63524c6c3c5ca8ab5d318965649
--- /dev/null
+++ b/third_party/WebKit/LayoutTests/http/tests/images/gif-animated-partial-load.html
@@ -0,0 +1,32 @@
+<img style="background: green" >
+<script>
+if (window.testRunner) {
+  testRunner.dumpAsTextWithPixelResults();
+  testRunner.waitUntilDone();
+}
+
+function loadAndStall()
+{
+  return "http://127.0.0.1:8000/resources/load-and-stall.php";
+}
+
+function gifImage()
+{
+  return "?name=../../../images/resources/count-down-color-test.gif&mimeType=image%2Fgif";
+}
+
+function testDone()
+{
+  window.testRunner && testRunner.notifyDone();
+}
+
+function runTest()
+{
+  document.querySelector("img").src = loadAndStall() + gifImage() + "&stallAt=4952&stallFor=60";
+  setTimeout(testDone, 1500);
+}
+
+window.onload = function() {
+  setTimeout(runTest, 0);
+}
+</script>