Switch to HarfBuzz on Mac and remove CoreText shaper

Source/web/tests/WebFrameTest.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 2858 matching lines @@
     WebRect rect, caret;
     webViewHelper.webViewImpl()->selectionBounds(caret, rect);
 
     float scale;
     IntPoint scroll;
     bool needAnimation;
     webViewHelper.webViewImpl()->computeScaleAndScrollForFocusedNode(webViewHelper.webViewImpl()->focusedElement(), scale, scroll, needAnimation);
     EXPECT_TRUE(needAnimation);
     // The edit box should be left aligned with a margin for possible label.
     int hScroll = editBoxWithText.x - leftBoxRatio * viewportWidth / scale;
-    EXPECT_NEAR(hScroll, scroll.x(), 1);
+    EXPECT_NEAR(hScroll, scroll.x(), 5);
     int vScroll = editBoxWithText.y - (viewportHeight / scale - editBoxWithText.height) / 2;
     EXPECT_NEAR(vScroll, scroll.y(), 1);
     EXPECT_NEAR(minReadableCaretHeight / caret.height, scale, 0.1);
 
     // The edit box is wider than the viewport when legible.
     viewportWidth = 200;
     viewportHeight = 150;
     webViewHelper.webView()->resize(WebSize(viewportWidth, viewportHeight));
     setScaleAndScrollAndLayout(webViewHelper.webView(), WebPoint(0, 0), 1);
     webViewHelper.webViewImpl()->selectionBounds(caret, rect);
@@ skipping 3739 matching lines @@
     EXPECT_EQ(1u, frameClient.navigationalDataReceivedCount());
 
     // Neither should a page reload.
     localFrame->reload();
     EXPECT_EQ(4u, frameClient.provisionalLoadCount());
     EXPECT_FALSE(frameClient.wasLastProvisionalLoadATransition());
     EXPECT_EQ(1u, frameClient.navigationalDataReceivedCount());
 }
 
 } // namespace