Update MANIFEST.json to current web-platform-tests.

This was forgotten in the last update. The README is also updated as a
reminder for future updates.
Fix <br> support
Merge pull request #3163 from mbrubeck/br

Fix `<br>` support [r=SimonSapin]
Fix comment syntax
Renew the auth token for pushing to github pages

It’s been leaked in a Travis log
Don’t show the githib token in Travis log
Merge pull request #3169 from Ms2ger/update-manifest

Update MANIFEST.json to current web-platform-tests; r=jdm
Use macro getters for input elements
Introduce the NativePropertyHooks struct.

This will be required for the cross-origin wrapper work.
Merge pull request #3176 from Manishearth/more-macros

Use macro getters for input elements: r=Ms2ger
Merge pull request #3175 from Ms2ger/propertyhooks

Introduce the NativePropertyHooks struct; r=jdm
Introduce ConstantSpec::get_value.

I'll need it for cross-origin wrappers as well.
Merge pull request #3177 from Ms2ger/ConstantSpec

Introduce ConstantSpec::get_value; r=jdm
Uppercase element.tagName for HTML elements only

Fixes #3146
Merge pull request #3147 from mbrubeck/tagname-upper

Uppercase element.tagName for HTML elements only r=Ms2ger
Make text decorations be independent display items.

The goal it to avoid having too much layout logic (which gets more complex in vertical text) in gfx code.
Fixup sideways text.