Made -webkit-print-color-adjust property independent.

Made -webkit-print-color-adjust property independent. Also updated
independent-inheritance-fast-path.html to include webkitPrintColorAdjust.
Also minor cleanup of make_computed_style_base.py, including removing a
redundant if and assignment to property_name.

Tested using independent-inheritance-fast-path.html.

BUG=628043

Review-Url: https://codereview.chromium.org/2578903002
Cr-Commit-Position: refs/heads/master@{#438797}
3 files changed