Add a detachAsStream to SkDynamicMemoryWStream.

R=reed@google.com

Committed: https://code.google.com/p/skia/source/detail?r=10171

Review URL: https://codereview.chromium.org/19677002

git-svn-id: http://skia.googlecode.com/svn/trunk@10178 2bbb7eff-a529-9590-31e7-b0007b416f81
4 files changed