Avoid modifying regex whitespace when not using x flag
Avoid modifying regex whitespace when not using x flag

This flag is what enables whitespace to be ignored, which is where we
are seeing the bug in xRegExp causing massive slowness. If we aren't
using this flag, we want to leave the original regexp in tact.

Galooshi/import-js,trotzig/import-js,trotzig/import-js,trotzig/import-js