Re-enable Object.observe and add enforcement for security invariants.

test/cctest/cctest.status

 # Copyright 2011 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
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 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
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@@ skipping 66 matching lines @@
   # BUG(3287).
   'test-cpu-profiler/SampleWhenFrameIsNotSetup': [PASS, FLAKY],
 
   ############################################################################
   # Slow tests.
   'test-api/Threading1': [PASS, ['mode == debug', SLOW]],
   'test-api/Threading2': [PASS, ['mode == debug', SLOW]],
   'test-api/Threading3': [PASS, ['mode == debug', SLOW]],
   'test-api/Threading4': [PASS, ['mode == debug', SLOW]],
   'test-strings/StringOOM*': [PASS, ['mode == debug', SKIP]],
-
-  # Object.observe is disabled.
-  'test-object-observe/*': [SKIP],
-  'test-microtask-delivery/*': [SKIP],
 }],  # ALWAYS
 
 ##############################################################################
 ['arch == arm64', {
 
   'test-api/Bug618': [PASS],
 
   # BUG(v8:2999).
   'test-cpu-profiler/CollectCpuProfile': [PASS, FAIL],
 
@@ skipping 220 matching lines @@
   'test-api/Float32Array' : [SKIP],
   'test-api/Float64Array' : [SKIP],
   'test-api/Regress2333' : [SKIP],
   'test-alloc/StressHandles' : [SKIP],
   'test-alloc/StressJS' : [SKIP],
   'test-accessors/HandleScopePop' : [SKIP],
   'test-accessors/Gc' : [SKIP],
 
 }],  # 'arch == nacl_ia32 or arch == nacl_x64'
 ]