Move naming related code in make_computed_style_base to name_utilities.

Currently make_computed_style_base is sprinkled with a lot of code
related to variable names and method names. These are common pieces of
logic that can be reused by other generators as well.

This patch tidies up make_computed_style_base by moving naming logic
to name_utilities.py.

BUG=628043

Review-Url: https://codereview.chromium.org/2756113002
Cr-Commit-Position: refs/heads/master@{#458635}
3 files changed