RFR(xs): 8155639: Remove STEP numbers from error reporting

[Thomas Stüfe]

Hi,

may I have reviews and a sponsor for the following small improvement?

Bug: https://bugs.openjdk.java.net/browse/JDK-8155639
webrev:
http://cr.openjdk.java.net/~stuefe/webrevs/8155639-STEP-number-removal/webrev.00/webrev/

Basically, this change proposes to get rid of the hand-coded STEP numbers
in error reporting in favour of using the __LINE__ macro.

The hand-coded step numbers are a constant source or errors, as they need
to maintained in monotonous order and if they are not, error reporting
steps are just quietly swallowed.

Using the __LINE__ macro would be self-maintaining and thus much more
robust.

Thank you!

Thomas