Matcher: Revert some needless differences vs. upstream OpenJDK 8u121-b13.

This CL reverts some pointless differences of Matcher.java vs. the upstream
version:

 - method ordering
 - naming of some parameters (value vs. b) and field (pattern vs.
   parentPattern)
 - minor documentation differences (probably accidental / forgotten
   when integrating previous upstream changes).
 - drop "throws IllegalStateException" declaration from intstart(int group).
   The method can still throw ISE, and is documented to do so, but the
   "throws" declaration is not necessary and upstream doesn't have it.

This is a refactoring only (no behavior change). It reduces the
difference between ojluni's vs upstream's Matcher.java from
49% (edit distance of 646 lines) to 34.8% different (459 lines).

This makes comparison against upstream code (eg. for verification
purposes) slightly simpler.

Bug: 35910877
Test: Treehugger

Change-Id: I28714e693db3905f7504e901da08a39a07dd7658
1 file changed