Assign color=0 in GrDrawState.cpp to stop tools from raising false alarms about uninit reads.

Assign color=0 in GrDrawState.cpp to stop tools from raising false alarms about uninit reads.

We were assigning color to oldColor but it in turn would never be read because the valid flags
would be cleared.

R=jvanverth@google.com
Committed: https://code.google.com/p/skia/source/detail?r=7886

[jvanverth1, 2013-02-27 17:36:36]

On 2013/02/27 17:32:00, bsalomon wrote:

LGTM

[bsalomon, 2013-02-27 18:43:50]

Committed patchset #1 manually as r7886 (presubmit successful).