Remove some unnecessary IE 6 hacks

We dropped JS support for IE 6. These workarounds for its bugs are no
longer necessary, because this code is no longer loaded. (The CSS
files modified are parts of modules that require JS support.)

We probably have a lot more, these just came up when grepping for
'IE6' and were obvious.

Change-Id: I7588b03f6ade699ddda4ec28be6c6f512e4b0ea8
Merge "Remove some unnecessary IE 6 hacks"