Do not call undefined internals.gc()

Undefined internals.gc() is called in onEventInFrame() and a TypeError
is thrown in current test, but the error is not visible because the
error is dispatched in another frame as mentioned in
https://crbug.com/606900 .
The test will call gc() instead of internals.gc() after and work as
intended after this patch.

Bug: 872138, 606900
Change-Id: I5d059e5ff7bea56b382f0e973282788427f5a306
Reviewed-on: https://chromium-review.googlesource.com/1186287
Commit-Queue: Yuki Yamada <yukiy@google.com>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585441}

third_party/WebKit/LayoutTests/fast/events/touch/gesture/gesture-tap-frame-removed.html

@@ -16,7 +16,7 @@ function onEventInFrame(e) {
     if (e.type == removalEventType) {
         debug('Removing iframe');
         target.parentNode.removeChild(target);
-        internals.gc();
+        gc();
     }
 }