Fix WebInstaller style

The WebInstaller don't use classes, so it broke after Vector skin changed
to use classes instead of ID's

See: Iae873906abcd8b2a986e5f728f0ce207256de770

Bug: 70190
Change-Id: Ia70498a0ee7c99d000790223c44feddce73a5416
Merge "Fix WebInstaller style"