PDF: Fix bug in weak pointer pattern.

For Canonicalized objects, only remove an object from the canonical list if it is the canonical object and not if it is an instance equal to the canonical object.

BUG=381
TBR=reed@google.com

Review URL: http://codereview.appspot.com/5330058

git-svn-id: http://skia.googlecode.com/svn/trunk@2559 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed