If the compiler is in ES6 mode, have acceptEcmaScript5 return true instead of crashing.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71873111
[NEW TYPE INFERENCE] Remove locations to improve reuse of types.

Unfortunately, we lose some inference with this change.
Depending on other perf improvements, we may re-add locations in the future.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71875828
Parse computed properties as method names in object literals and classes, and report an error if we try to transpile them.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71875854
Improved the handling of type transformation keywords
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71876326
[NEW TYPE INFERENCE] Optimize ObjectType.joinSets to make fewer hashCode calls
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71876456
Fix Es6TemplateLiterals to recognize more types of tagged template literals.

This fixes CallExpression, CommaExpression and MemberExpression in the Traceur
test suite for template literals.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71883815
Add test for transpiling methods in object literals that have a computed property as a name, since it happens to already work.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71924087
Enable CheckMissingReturn by default.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71931457
Added the logic for evaluating basic expressions of the type transformation language such as type variables and basic type predicates like type('typename') using the old type system.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71937605
Don't retain a map containing all JS comments in the entire program.

This map is only used in IDE mode, so keep it only in IDE mode.
-------------
Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=71941397