Class transpilation: Add a synthetic constructor which calls the superclass constructor, if the user didn't provide one.

Fixes #690
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=79785014
[NEW TYPE INFERENCE] Create less garbage from namespaces in simpleInferExprType
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=79800519
Parser: Reject arrow functions with a newline before the arrow.

This fixes one of the cases on http://kangax.github.io/compat-table/es6/ (issue #700)
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=79800905