Change global const handling to silently ignore redeclarations

test/es5conform/es5conform.status

 # Copyright 2009 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 23 matching lines @@
 # Non UTF8 characters in test files.
 chapter10/10.4/10.4.2/10.4.2-3-c-2-s: FAIL_OK
 chapter10/10.4/10.4.2/10.4.2-3-c-1-s: FAIL_OK
 chapter10/10.4/10.4.2/10.4.2-2-c-1: FAIL_OK
 
 # We do not implement the error chekcs specified in the production rules
 # of 11.1.5 (Object initializer).
 # We are compatible with Safari and Firefox.
 chapter11/11.1/11.1.5: UNIMPLEMENTED
 
-# We do not have a global object called 'global' as required by tests.
-chapter15/15.1: FAIL_OK
-
-# NaN is writable. We are compatible with JSC.
-chapter15/15.2/15.2.3/15.2.3.3/15.2.3.3-4-178: FAIL_OK
-# Infinity is writable. We are compatible with JSC.
-chapter15/15.2/15.2.3/15.2.3.3/15.2.3.3-4-179: FAIL_OK
-# undefined is writable. We are compatible with JSC.
-chapter15/15.2/15.2.3/15.2.3.3/15.2.3.3-4-180: FAIL_OK
-
 # Our Function object has an "arguments" property which is used as a
 # non-property in the test.
 chapter15/15.2/15.2.3/15.2.3.3/15.2.3.3-4-183: FAIL_OK
 
 # Our Function object has a "caller" property which is used as a
 # non-property in in the test.
 chapter15/15.2/15.2.3/15.2.3.3/15.2.3.3-4-184: FAIL_OK
 
 # Our function object has a name property which is used as a
 # non-property in the test.
@@ skipping 282 matching lines @@
 chapter15/15.3/15.3.2/15.3.2.1/15.3.2.1-11-6-s: FAIL
 
 # Array.prototype.reduce - null passed as thisValue to strict callbackfn
 # Invalid test case: http://es5conform.codeplex.com/workitem/29085
 chapter15/15.4/15.4.4/15.4.4.21/15.4.4.21-9-c-ii-4-s: FAIL
 
 [ $arch == mips ]
 
 # Skip all tests on MIPS.
 *: SKIP