[wasm] Enable local iframe test.

It appears the original reason this bug was disabled does not reproduce
anymore; also fixed unrelated test bug (it's unrelated to the original
reason the test was disabled, because, originally, instantiation wasn't
working full stop because of differences in contexts. Test bug just
wasn't receiving data correctly.)

BUG=chromium:700788

Review-Url: https://codereview.chromium.org/2822193003
Cr-Commit-Position: refs/heads/master@{#465610}

third_party/WebKit/LayoutTests/TestExpectations

@@ -2697,8 +2697,6 @@ crbug.com/708499 virtual/wheelscrolllatching/fast/compositor-wheel-scroll-latchi
 
 crbug.com/706091 [ Linux ] virtual/wheelscrolllatching/fast/events/wheel/wheel-scroll-latching-on-scrollbar.html [ Failure Pass ]
 
-crbug.com/700788 virtual/enable_wasm/http/tests/wasm/wasm_local_iframe_test.html [ Failure ]
-
 # Sheriff failures 2017-04-03
 # Should be [ Crash Pass ], but this has a commented out [ Skip ] expectation
 # for Mac earlier in the file, so just skip it everywhere.

third_party/WebKit/LayoutTests/http/tests/wasm/resources/frame.html

 <script>
-  function listener(event) {
-    var mod = event.data;
-    try {
-      var i = new WebAssembly.Instance(mod);
-      var ans = i.exports.increment(42);
-      event.source.postMessage(ans, "*");
-    } catch (e) {
-      event.source.postMessage(e, "*");
-    }
+function listener(event) {
+  var mod = event.data;
+  try {
+    var i = new WebAssembly.Instance(mod);    
+    var ans = i.exports.increment(42);
+    event.source.postMessage(ans, event.origin);
+  } catch (e) {
+    event.source.postMessage(e, event.origin);
   }
+}
 
-  if (window.addEventListener){
-    addEventListener("message", listener, false)
-  } else {
-    attachEvent("onmessage", listener)
-  }
+if (window.addEventListener){
+  addEventListener("message", listener, false)
+} else {
+  attachEvent("onmessage", listener)
+}
 </script>

third_party/WebKit/LayoutTests/http/tests/wasm/wasm_local_iframe_test.html

@@ -10,7 +10,7 @@
     var ans = await new Promise((resolve, reject) => {
       var iframe = document.getElementById("iframe").contentWindow;
       iframe.postMessage(mod, '*');
-      iframe.onmessage = event => resolve(event.data);
+      window.addEventListener("message", (reply) => resolve(reply.data), false);
     });
     assert_equals(ans, 43);
   }, "send wasm module to iframe");