Change GitCL to initialize git executable name on Windows.

third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py

Index: third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py b/third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py
index cb994a7e4bdc4c8764fe832957c981c6e6723fde..52e82e0b15740bad24207898c0929c349bdaf380 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py
@@ -69,9 +69,9 @@ class MockHost(MockSystemHost):
 
     def git(self, path=None):
         if path:
-            return MockGit(cwd=path, filesystem=self.filesystem, executive=self.executive)
+            return MockGit(cwd=path, filesystem=self.filesystem, executive=self.executive, platform=self.platform)
         if not self._git:
-            self._git = MockGit(filesystem=self.filesystem, executive=self.executive)
+            self._git = MockGit(filesystem=self.filesystem, executive=self.executive, platform=self.platform)
         # Various pieces of code (wrongly) call filesystem.chdir(checkout_root).
         # Making the checkout_root exist in the mock filesystem makes that chdir not raise.
         self.filesystem.maybe_make_directory(self._git.checkout_root)