Treat 'class', 'extends', 'import', 'export' as reserved when 'inESNext'.
Handle 'class' statements. Reuses the code for handling object literals.
Add 'classexpression' handling.
Forgot to make class bodies strict.
Rename function param 'classdef' to 'isclassdef'.
Factor out common code for class statements and class expressions.
Extend strictness to cover the entire class definition.
Remove unused vars.
Formatting only: add newline.
Allow more exact transitions in keyword filtering between strict and non-strict.
Add test for 'class' parsing and strict-mode keywords.
Merge branch 'master' into class

Conflicts:
	tests/stable/unit/parser.js

Fixed by keeping both tests.
Fix missing semicolon.
Treat methods and static methods separately in checking for duplicates.
Require that constructors be regular methods.
Check for methods named 'prototype'.
Limit 'constructor' getter/setter checks to class definitions.
Comments: reformat and add some more relevant quotes from the ES6 spec.
Fix indentation.
Fix error message calls.