Bug 937751 - Followup to compile with clang versions that treat |struct S; struct __attribute__((visibility("default"))) S {};| as an error.  rs=mccr8

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extra : rebase_source : 97d6faaaa484a9544d2683c4a1af5c3e044fa2d3
Bug 940033 - js::HashMapEntry::{key,value} fields should be private, with accessors, and the former should expose a const reference.  r=jimb

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extra : rebase_source : 439d194ed15bf87e9643c9c09d4512ff7f616fcc