Cleanup GrTextBlob management code

* cacheBlob -> cachedBlob
* listPaint -> blobPaint
* variable contextPriv
* variable colorInfo
* color -> initialVertexColor
* filterColor -> drawingColor

Change-Id: I36c6f885f8a4d041d9b0d84f787999d5648675ac
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/258807
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
1 file changed