Remove underscore from classes WebInstaller_*

Part of program to remove underscores from class names. Checked core and
675 extensions for occurrences. All uses are in core in core are updated
in this patch. There are no uses in Gerrit extensions.

Change-Id: I6150c2d3f5a18496da5bcdcadc5d8982b70bec7a
Merge "Remove underscore from classes WebInstaller_*"