Initialize mColor to fix UMR. b=480032 r+sr=vladimir

gfx/src/thebes/nsThebesRenderingContext.cpp

@@ -81,8 +81,9 @@ static NS_DEFINE_CID(kRegionCID, NS_REGION_CID);
 
 NS_IMPL_ISUPPORTS1(nsThebesRenderingContext, nsIRenderingContext)
 
-nsThebesRenderingContext::nsThebesRenderingContext() :
-    mLineStyle(nsLineStyle_kNone)
+nsThebesRenderingContext::nsThebesRenderingContext()
+  : mLineStyle(nsLineStyle_kNone)
+  , mColor(NS_RGB(0,0,0))
 {
 }