Share precompiled header setup for blink between Windows and Mac.

third_party/WebKit/Source/core/win/Precompile-core.h

Index: third_party/WebKit/Source/core/win/Precompile-core.h
diff --git a/third_party/WebKit/Source/core/win/Precompile-core.h b/third_party/WebKit/Source/core/win/Precompile-core.h
deleted file mode 100644
index 53ba37a3b519065d0ec449061795a90670e4c3ca..0000000000000000000000000000000000000000
--- a/third_party/WebKit/Source/core/win/Precompile-core.h
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#if defined(PrecompileCore_h_)
-#error You shouldn't include the precompiled header file more than once.
-#endif
-#define PrecompileCore_h_
-
-#include "build/win/Precompile.h"
-
-// In Blink a lot of operations center around dom and Document, or around
-// layout/rendering and LayoutObject. Those two headers are in turn pulling
-// in large parts of Blink's other headers which means that every compilation
-// unit is compiling large parts of Blink. By precompiling Document.h
-// and LayoutObject.h we only have to compile those parts once rather
-// than 1500 times. It can make a large difference in compilation
-// times (3-4 times faster).
-#include "core/dom/Document.h"
-#include "core/layout/LayoutObject.h"