fix($exceptionHandlerProvider): call `inject()` to run tests

In the current angular-mocksSpec, the tests for $exceptionHandlerProvider
call `module` to run tests on `$exceptionHandlerProvider.mode()`, but do
not call `inject()` to pump the module definitions.
No, because the code in the `module()` block does not get executed. I have a branch that verifies the (lack of) executing code using `console.log`.