Review request for backport of JDK-8143896: java.lang.Long is implicitly converted to double

[Hannes Wallnoefer]

Please review backport of JDK-8143896: java.lang.Long is implicitly 
converted to double:

http://cr.openjdk.java.net/~hannesw/8143896/webrev-8u/
This builds on the JDK-8144020 backport which I posted earlier. Some 
manual merging was necessary in runtime/JSType.java and 
objects/NativeNumber.java. The backport also does not contain the 
changes to the Parser API test as that is not available in JDK 8.

Thanks,
Hannes