Tiny refactoring that will make it easier for Es6ToEs3Converter and Es6ConvertSuper to share code
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=79689295
[NEW TYPE INFERENCE] Automatically convert {number, string, boolean} to {Number, String, Boolean}
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=79702204
Make sure that SPREAD nodes inside super() calls are converted correctly.

Do this by separating the conversion of SUPER nodes into a separate pass, so that the order in which conversions happen is clearer and less error-prone.

Fixes #701 on Github.
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=79708910