am f78acacb: Fix the \'wobbling fixed elements\' bug. Cherry-picked from master. This CL has a corresponding C++ counterpart (https://android-git.corp.google.com/g/#change,51149)

Merge commit 'f78acacb0d7a8e4d9e85a1cd6eed0f6bb38d6776' into froyo-plus-aosp

* commit 'f78acacb0d7a8e4d9e85a1cd6eed0f6bb38d6776':
  Fix the 'wobbling fixed elements' bug.