remove SK_SUPPORT_LEGACY_COLORTYPE as all callsites have been updated

BUG=

Review URL: https://codereview.chromium.org/134203002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244255 0039d316-1c4b-4281-b951-d872f2087c98

skia/skia_common.gypi

@@ -143,7 +143,6 @@
       'GR_GL_CUSTOM_SETUP_HEADER="GrGLConfig_chrome.h"',
       'SK_ENABLE_LEGACY_API_ALIASING=1',
       'SK_ATTR_DEPRECATED=SK_NOTHING_ARG1',
-      'SK_SUPPORT_LEGACY_COLORTYPE=1',
       'GR_GL_IGNORE_ES3_MSAA=0',
       'SK_SUPPORT_LEGACY_ONLOCKPIXELS',
     ],