The gallery repository history has been rewritten (see flutter/gallery#87), so updating to HEAD commit
This rolls the engine from: 965fbbed1776545ee681cb57f3fb1d0c2000bbcb to b5f5e6332cb4987e9e38ffaa267733ec0a8705ba. A Dart SDK roll in this range changed the format of the compileExpression RPC VMService endpoint, necessitating a tool patch.