Revert 20313 - "Ship promises and weak collections"

test/mjsunit/regress/regress-crbug-350864.js

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-// Flags: --harmony-symbols
+// Flags: --harmony_symbols --harmony-weak-collections
 
 var v0 = new WeakMap;
 var v1 = {};
 v0.set(v1, 1);
 var sym = Symbol();
 v1[sym] = 1;
 var symbols = Object.getOwnPropertySymbols(v1);
 assertArrayEquals([sym], symbols);