Bug 872735, part 1 - Remove isEmptySemicolon from the ParseHandler protocol. It was only used for a warning about "if (foo);". r=Waldo.
Bug 872735, part 2 - Remove noteLValue from the handler protocol. The main point of this change is to remove the noteLValue method from SyntaxParseHandler, because who knows what that is supposed to mean (anyway it is never called). r=Waldo.
Bug 872735, part 2a - Rename ParseNode::noteLValue -> markAsAssigned and add an assertion about pn_op, as requested in review. rs=Waldo.
Bug 872735, part 3 - Add PNK_LABEL for labeled statement nodes. Remove ForgetUse. r=Waldo.
Bug 872735, part 4 - Remove setBinaryRHS from the ParseHandler protocol. It was only used in parsing switch statements. It is replaced by a newCaseOrDefault method. r=Waldo.
Bug 872735, part 5 - Remove newNullary from the ParseHandler protocol. It is only used for array holes; replace it with a newElision method. Add PNK_ELISION to distinguish elisions from sequence expressions (which use PNK_COMMA). r=Waldo.
Bug 881056 - Remove unused hasFunctionStmt parameter from some Parser methods. r=bhackett.