X87: Reimplement Maps and Sets in JS
port 909500aa1db9789b68e101045a6359a7fcb30e83 (r27605)
original commit message:
Previously, the only optimized code path for Maps and Sets was for String keys.
This was achieved through an implementation of various complex operations
in Hydrogen. This approach was neither scalable nor forward-compatible.
This patch adds the necessary intrinsics to implement Maps and Sets almost entirely
in JS. The added intrinsics are:
With these additions, as well as a few changes to what's exposed as runtime functions,
most of the C++ code backing Maps and Sets is gone (including both runtime code in
objects.cc and Crankshaft in hydrogen.cc).