Add basic support for web fonts. Synchronous loading only

[glennw]

for now, and only deals with TTF format fonts.

For an example, try loading http://icons.marekventur.de

[hoppipolla-critic-bot]

Critic review: https://critic.hoppipolla.co.uk/r/2000

This is an external review system which you may optionally use for the code review of your pull request.

In order to help critic track your changes, please do not make in-place history rewrites (e.g. via git rebase -i or git commit --amend) when updating this pull request.

[pcwalton]

Whoa, sweet.

[pcwalton]

This should eventually get a reftest. I recommend using the Ahem font, as it was explicitly designed for this: http://www.w3.org/Style/CSS/Test/Fonts/Ahem/

[Ms2ger]

We need to start running the test for missing license headers on travis

[SimonSapin]

I’m reviewing the parsing code.

[SimonSapin]

Partial review done on Critic.

[glennw]

Thanks for reviewing! I've pushed fixes for those and updated the critic review.

[glennw]

**** NOTE: Even when this review is completed, it can't be merged until servo/core-graphics-rs#24 has landed and had submodule ptrs updated in servo ****

** The PR above has now landed in master, and travis is now passing - so this can be merged once the review is completed. **

[glennw]

r? @SimonSapin

[glennw]

Rebased and updated to support new url parser.

[SimonSapin]

Fix the FIXME by replacing the .unwrap() by .unwarp_or_else(|| Url::parse("about:invalid")).

[glennw]

Fixed

[glennw]

Would it be better if I split this into a few smaller PRs that are easier to review (e.g. CSS parsing separate from the platform specific font support etc)?

[SimonSapin]

I don’t think it would really help. We’d still need to be better than this at assigning reviewers :]

[larsbergstrom]

Is this set to merge? All issues appear addressed.

[glennw]

I kicked off a travis build this morning to make sure it is still green.

[larsbergstrom]

r+