Track: Revert some needless differences vs upstream in Matcher.java

Android Matcher.start(int) declared "throws IllegalStateException",
which is correct but redundant. Upstream OpenJDK8u121-b13 does not
have this declaration. Another CL in this topic drops the declaration,
without changing behavior.

Bug: 35910877
Test: Treehugger

Change-Id: I59778f13f0df8bd4112af4edc25ee5a93084ae35