HTML-CSS gets bounding boxes incorrect

The 2.5.1 patch introduced an error in the final bounding box used for formulas in HTML-CSS output. See this StackExchange post for examples. This is due to the changes made to recover some of the speed lost when measuring the final mathematics. Two issues are present: the exactW value should have been set to false before doing the final measuring (otherwise it will not remeasure), and the MathJax_Processed class should be removed before the remeasure, not after it (otherwise you get width 0).

This is also related to issue #1086 (closed), though that has additional reasons as well.