master
8245455: Remove alternative StringConcatFactory strategies
8347817: Timeouts running test/jdk/java/lang/String/concat/HiddenClassUnloading.java with fastdebug builds
8356152: String.concat can throw StringIndexOutOfBoundsException
4511638: Double.toString(double) sometimes produces incorrect results
8297530: java.lang.IllegalArgumentException: Negative length on strings concatenation
8247681: Improve bootstrapping of unary concatenations
8245959: Extend String concat testing to account for folded constants
8267773: PhaseStringOpts::int_stringSize doesn't handle min_jint correctly
8187443: Forest Consolidation: Move files to unified layout