Start using more typed units in the compositor

Now that rust-layers is starting to support typed units, we can use
them more thoroughly in the compositor. This is a step toward removing
as many untyped units as possible.
Share code between HTMLScriptElement:Text and Node:GetTextContent

Added a function in Node called collect_text_contents which is called
from both places.

Fixes #3157
Merge pull request #3189 from gilles-leblanc/issue-3157

Share code between HTMLScriptElement:Text and Node:GetTextContent; r=Manishearth
Disable ssl on android as openssl needs to be added to build system.
Merge pull request #3192 from glennw/disable-android-ssl

Disable ssl on android as openssl needs to be added to build system.
Revert "Add tests for the bit_struct! macro."

This reverts commit dd44a7d24affbef1841bf8aa4c8c0e9c3c4989f0.
Revert "fixup! Move PropertyBitField to a syntax extension."

This reverts commit 653f257029466fcc587d6ba17495a663cbd1693b.
Revert "Move PropertyBitField to a syntax extension."

This reverts commit d6002a0a50f4c9fab7bcaf592b296123d33ac212.
Merge pull request #3194 from glennw/android-build

Revert syntax extension for now, as it causes issues with cross compiling for android.
Move the script type and language checks into HTMLScriptElement.

This is IMO a more sensible place for them to live, and prepares for the
demise of hubbub_html_parser.rs, as we move to html5ever.
Merge pull request #3196 from Ms2ger/script

Move the script type and language checks into HTMLScriptElement.
Merge pull request #3173 from mrobinson/typed-units-1

Start using more typed units in the compositor