Delegate marking should be at the right location.

Whitespaces and comments skipping should be carried out before
calling the syntax tree delegate location marking functions.

https://code.google.com/p/esprima/issues/detail?id=355
Simplify comment collection.

Instead of two separate functions, now skipComment can also collect all
line and block comments, making scanComment() not necessary anymore.

The most cyclomatic function now falls into scanRegExp().

https://code.google.com/p/esprima/issues/detail?id=396