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.
Merge pull request #177 from webbedspace/opera15

Merge Opera 15+ into the Chrome columns. Closes #153