[wasm] Fail remote post message test if about:blank can't open

Instead of waiting until the test harness timeouts the test, we
wait for a set period of time for the about:blank window to open,
after which we fail the test.

Bug: chromium:765738
Change-Id: I8635c19683a3791801bc3e75a3fc3bf16872b6f2
Reviewed-on: https://chromium-review.googlesource.com/676283
Commit-Queue: Brad Nelson <bradnelson@chromium.org>
Reviewed-by: Brad Nelson <bradnelson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#504467}

third_party/WebKit/LayoutTests/http/tests/wasm/wasm_remote_postMessage_test.https.html

@@ -10,14 +10,19 @@ promise_test(async function() {
   assert_true(mod instanceof WebAssembly.Module);
   var remote;
   await new Promise((resolve, reject) => {
+    var nr_of_tries = 0;
     var i = setInterval(()=>{
       try {
         remote.document;
+        ++nr_of_tries;
+        if(nr_of_tries > 30) {
+          reject();
+        }
       } catch(e) {
         clearInterval(i);
         resolve();
       }
-    }, 100);
+    }, 1000);
     remote = window.open("about:blank");
     remote.opener = null;
     remote.location = remote_loc;