Auto merge of #135 - asajeffrey:more_static_atoms, r=SimonSapin
Auto merge of #135 - asajeffrey:more_static_atoms, r=SimonSapin

Added more atoms to static_atom_list.

The list now includes:

* all the CSS attributes and DOM events used by Servo,
* the element ids such as #text used by Servo,
* the User Agent strings such as Mozilla used by Servo.

At this point, every string constant in the Servo code base can be atomized.

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servo/string-cache