Reland "Enable Object.observe by default" again

src/flag-definitions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 161 matching lines @@
 DEFINE_bool(harmony_typeof, false, "enable harmony semantics for typeof")
 DEFINE_bool(harmony_scoping, false, "enable harmony block scoping")
 DEFINE_bool(harmony_modules, false,
             "enable harmony modules (implies block scoping)")
 DEFINE_bool(harmony_symbols, false,
             "enable harmony symbols (a.k.a. private names)")
 DEFINE_bool(harmony_promises, false, "enable harmony promises")
 DEFINE_bool(harmony_proxies, false, "enable harmony proxies")
 DEFINE_bool(harmony_collections, false,
             "enable harmony collections (sets, maps, and weak maps)")
-DEFINE_bool(harmony_observation, false,
-            "enable harmony object observation (implies harmony collections")
 DEFINE_bool(harmony_generators, false, "enable harmony generators")
 DEFINE_bool(harmony_iteration, false, "enable harmony iteration (for-of)")
 DEFINE_bool(harmony_numeric_literals, false,
             "enable harmony numeric literals (0o77, 0b11)")
 DEFINE_bool(harmony_strings, false, "enable harmony string")
 DEFINE_bool(harmony_arrays, false, "enable harmony arrays")
 DEFINE_bool(harmony_maths, false, "enable harmony math functions")
 DEFINE_bool(harmony, false, "enable all harmony features (except typeof)")
 DEFINE_implication(harmony, es_staging)
 DEFINE_implication(harmony, harmony_scoping)
 DEFINE_implication(harmony, harmony_modules)
 DEFINE_implication(harmony, harmony_symbols)
 DEFINE_implication(harmony, harmony_promises)
 DEFINE_implication(harmony, harmony_proxies)
 DEFINE_implication(harmony, harmony_collections)
-DEFINE_implication(harmony, harmony_observation)
 DEFINE_implication(harmony, harmony_generators)
 DEFINE_implication(harmony, harmony_iteration)
 DEFINE_implication(harmony, harmony_numeric_literals)
 DEFINE_implication(harmony, harmony_strings)
 DEFINE_implication(harmony, harmony_arrays)
 DEFINE_implication(harmony, harmony_maths)
 DEFINE_implication(harmony_promises, harmony_collections)
 DEFINE_implication(harmony_modules, harmony_scoping)
-DEFINE_implication(harmony_observation, harmony_collections)
 
 // Flags for experimental implementation features.
 DEFINE_bool(packed_arrays, true, "optimizes arrays that have no holes")
 DEFINE_bool(smi_only_arrays, true, "tracks arrays with only smi values")
 DEFINE_bool(compiled_keyed_dictionary_loads, true,
             "use optimizing compiler to generate keyed dictionary load stubs")
 DEFINE_bool(clever_optimizations, true,
             "Optimize object size, Array shift, DOM strings and string +")
 DEFINE_bool(pretenuring, true, "allocate objects in old space")
 // TODO(hpayer): We will remove this flag as soon as we have pretenuring
@@ skipping 697 matching lines @@
 #undef DEFINE_ALIAS_float
 #undef DEFINE_ALIAS_args
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA