Moved clear property to be generated in ComputedStyleBase.

Move the inherited property clear and its enum, EClear,
to be generated in ComputedStyleBase. Also moved getter / setter /
initial value methods to be generated in ComputedStyleBase.

This also reduces the size of ComputedStyle by 8 bytes.

BUG=628043

Review-Url: https://codereview.chromium.org/2656733002
Cr-Commit-Position: refs/heads/master@{#447206}
4 files changed