My change 983b75e1cf broke
-warn-long-expression-type-checking because now the
ExpressionTimer is not instantiated by default and that
entire code path is skipped.
Change it so that if -warn-long-expression-type-checking
is passed in, we still start the timer, we just don't
ever consider it to have 'expired'.
Fixes rdar://problem/152998878.
We saw a failure of this test on Linux at some point, and disabled
it. It looks like it may have been due to the fact that the
`%target-typecheck-verify-swift` provides the filename, but we
explicitly provide the filename in the test invocation here as well.
I'm going to re-enable and see if we can get through tests on all
supported platforms.
Generates a warning for any expression that takes longer than <limit>
milliseconds to type check. This compliments the existing
-warn-long-function-body=<limit> option.
