Make Minerva skin opt out of parsoid style module

These styles are mostly Vectorish, so shouldn't be applied to the
Minerva skin that is provided in MobileFrontend.

We set our own parsoid styles in
VisualEditorOverlay.less.

Change-Id: I11a75c5552fa14ad119ad60bb5fa3f6185582429
Dependency: I5de12c97108dcb6e41ac8c34b17ff993d2e65249
Merge "Make Minerva skin opt out of parsoid style module"