[compositorworker] Avoid deadlock issue caused by importScript

third_party/WebKit/LayoutTests/virtual/threaded/fast/compositorworker/resources/proxy-disconnect.js

Index: third_party/WebKit/LayoutTests/virtual/threaded/fast/compositorworker/resources/proxy-disconnect.js
diff --git a/third_party/WebKit/LayoutTests/virtual/threaded/fast/compositorworker/resources/proxy-disconnect.js b/third_party/WebKit/LayoutTests/virtual/threaded/fast/compositorworker/resources/proxy-disconnect.js
index 78477212f7826ca9508f4f87f409a19b1b13ba0e..06513ecb214af34b49cd62d475d3da859e8aea8a 100644
--- a/third_party/WebKit/LayoutTests/virtual/threaded/fast/compositorworker/resources/proxy-disconnect.js
+++ b/third_party/WebKit/LayoutTests/virtual/threaded/fast/compositorworker/resources/proxy-disconnect.js
@@ -1,5 +1,3 @@
-self.importScripts('worker-common.js');
-
 self.onmessage = function(msg) {
   awaitProxyInit(msg.data).then((proxy) => {
     proxy.opacity;
@@ -12,3 +10,14 @@ self.onmessage = function(msg) {
     }
   });
 }
+
+function awaitProxyInit(proxy) {
+  return new Promise((resolve, reject) => {
+    function check() {
+      if (proxy.initialized)
+        resolve(proxy);
+      requestAnimationFrame(check);
+    }
+    requestAnimationFrame(check);
+  });
+}