Revert "change SkColorTable to be immutable"

This reverts commit 1c0ff422868b3badf5ffe0790a5d051d1896e2f7.

BUG=

Review URL: https://codereview.chromium.org/26709002

git-svn-id: http://skia.googlecode.com/svn/trunk@11677 2bbb7eff-a529-9590-31e7-b0007b416f81
16 files changed