Rename RenderLayer::updateLayerPositions to updateLayerPositionRecursive

We also have a function called updateLayerPosition and having both was
confusing.

Review URL: https://codereview.chromium.org/327053002

git-svn-id: svn://svn.chromium.org/blink/trunk@175922 bbb929c8-8fbe-4397-9dbb-9b2b20218538