With Compact Themes and RTL locales, the URL bar becomes blurry on hover. This
seems to be triggered by the combination:
```
transform: scaleX(-1);
clip-path: none;
```
The transform is was only applied to position the clip-path correctly, so it's
actually not needed by Compact Themes.
MozReview-Commit-ID: KKQt6h6VzT7
For selected tabs, the Compact Themes use bright blue tab background colors,
which makes the blue loading icon hard to see. For this state, use a white
loading icon instead.
MozReview-Commit-ID: 5P2VWgR4Iue
This commit does the following:
* Install two lightweight themes instead of one
* Introduce a build config to install the themes instead of relying on channel: INSTALL_COMPACT_THEMES
* Change browser-compacttheme to use the new themes instead of the old one
* Remove inferBrightness since the lwt colors are part of the compact theme definision, as opposed
to the devedition theme which could be light or
* Update CSS to use :-moz-lwtheme-darktext and :-moz-lwtheme-brighttext instead of [devtoolstheme]
MozReview-Commit-ID: 4gKU68drlE2
