[MERGE #6130 @zenparsing] Unflag object rest/spread

Merge pull request #6130 from zenparsing:enable-obj-rest-spread

For reference:

- Object spread PR: #5268
- Object rest PR: #5498

The functionality is implemented in the JIT using helper calls. For destructuring rest, it uses GC'd arrays for tracking which computed property names have already been pulled out of the object.

A PR exists for updating our fuzzers to generate the new syntax.

Author: Kevin Smith

lib/Common/ConfigFlagsList.h

@@ -659,7 +659,7 @@ PHASE(All)
 #define DEFAULT_CONFIG_ES6Spread               (true)
 #define DEFAULT_CONFIG_ES6String               (true)
 #define DEFAULT_CONFIG_ES6StringPrototypeFixes (true)
-#define DEFAULT_CONFIG_ES2018ObjectRestSpread  (false)
+#define DEFAULT_CONFIG_ES2018ObjectRestSpread  (true)
 
 #ifndef DEFAULT_CONFIG_ES6PrototypeChain
 #ifdef COMPILE_DISABLE_ES6PrototypeChain