ES6: Merged Opera 15+ with Chrome

Since Opera 15+ and Chrome use the same JS engine, and are lockstep
with releases, it makes sense to combine the two. Fixes #153.
Marked Chrome < 35 obsolete
Updated Chrome 37 results

The latest Canary build seems to support for..of and arrows.
Feature name column is no longer dimmed

When a single feature row is selected, the other columns' names are no
longer dimmed. Fixes #128.
Obsolete browser columns are partially desaturated

New feature: when "show obsolete browsers" is enabled, the additional
columns are drawn using slightly desaturated colours to offset them
from the current browsers.