Remove VisiblePositionForViewportPoint()

WebLocalFrameImpl::VisiblePositionForViewportPoint() is unused, remove it.
Reduce usage of VisiblePosition also.

Bug: 657237
Change-Id: I9a6588c856a68ad88975771cab206e7e19a29fd7
Reviewed-on: https://chromium-review.googlesource.com/c/1297850
Commit-Queue: David Bokan <bokan@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602340}

third_party/blink/renderer/core/frame/web_local_frame_impl.cc

@@ -1457,12 +1457,6 @@ void WebLocalFrameImpl::SetCaretVisible(bool visible) {
   GetFrame()->Selection().SetCaretVisible(visible);
 }
 
-VisiblePosition WebLocalFrameImpl::VisiblePositionForViewportPoint(
-    const WebPoint& point_in_viewport) {
-  return VisiblePositionForContentsPoint(
-      GetFrame()->View()->ViewportToFrame(point_in_viewport), GetFrame());
-}
-
 WebPlugin* WebLocalFrameImpl::FocusedPluginIfInputMethodSupported() {
   WebPluginContainerImpl* container = GetFrame()->GetWebPluginContainer();
   if (container && container->SupportsInputMethod())

third_party/blink/renderer/core/frame/web_local_frame_impl.h

@@ -424,9 +424,6 @@ class CORE_EXPORT WebLocalFrameImpl final
   // Otherwise creates it and then returns.
   TextFinder& EnsureTextFinder();
 
-  // Returns a hit-tested VisiblePosition for the given point
-  VisiblePosition VisiblePositionForViewportPoint(const WebPoint&);
-
   void SetFrameWidget(WebFrameWidgetBase*);
 
   // TODO(dcheng): Remove this and make |FrameWidget()| always return something