Correct Skia source file exclusion when building on Windows.

TBR=reed@google.com
BUG=None
TEST=None
Review URL: http://codereview.chromium.org/7328008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@91778 0039d316-1c4b-4281-b951-d872f2087c98

skia/skia.gyp

@@ -812,7 +812,7 @@
         [ 'OS == "win"', {
           'sources!': [
             '../third_party/skia/src/core/SkMMapStream.cpp',
-            '../third_party/skia/src/ports/SkTime_Unix.cc',
+            '../third_party/skia/src/ports/SkTime_Unix.cpp',
             'ext/SkThread_chrome.cc',
           ],
           'include_dirs': [