Fix resizing on disabled form controls.

Events would get marked as consumed when on top of the resize controller.
Deal with that situation so that we allow the resize to occur on
disabled form controls.

BUG=762709
TBR=dtapuska@chromium.org

(cherry picked from commit 9e011ce)

Change-Id: I17f8ae25541f9e4665d4a4bbcfef9e719f12f454
Reviewed-on: https://chromium-review.googlesource.com/951911
Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#541234}
Reviewed-on: https://chromium-review.googlesource.com/955742
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Cr-Commit-Position: refs/branch-heads/3359@{#94}
Cr-Branched-From: 66afc5e-refs/heads/master@{#540276}

third_party/WebKit/Source/core/input/EventHandler.cpp

@@ -661,7 +661,10 @@ WebInputEventResult EventHandler::HandleMousePressEvent(
       EventTypeNames::mousedown, mev.InnerNode(), mev.CanvasRegionId(),
       mev.Event(), Vector<WebMouseEvent>());
 
-  if (event_result == WebInputEventResult::kNotHandled && frame_->View()) {
+  // Disabled form controls still need to resize the scrollable area.
+  if ((event_result == WebInputEventResult::kNotHandled ||
+       event_result == WebInputEventResult::kHandledSuppressed) &&
+      frame_->View()) {
     LocalFrameView* view = frame_->View();
     PaintLayer* layer =
         mev.InnerNode()->GetLayoutObject()