<rdar://problem/13380794>

Reviewed by Mark Hahnenberg.

Fixes the following build failures:

    Source/JavaScriptCore/API/tests/testapi.mm:106:1: error: no 'assign', 'retain', or 'copy' attribute is specified - 'assign' is assumed [-Werror,-Wobjc-property-no-attribute]
    @property JSValue *onclick;
    ^
    Source/JavaScriptCore/API/tests/testapi.mm:106:1: error: default property attrib ute 'assign' not appropriate for non-GC object [-Werror,-Wobjc-property-no-attribute]
    Source/JavaScriptCore/API/tests/testapi.mm:107:1: error: no 'assign', 'retain', or 'copy' attribute is specified - 'assign' is assumed [-Werror,-Wobjc-property-no-attribute]
    @property JSValue *weakOnclick;
    ^
    Source/JavaScriptCore/API/tests/testapi.mm:107:1: error: default property attribute 'assign' not appropriate for non-GC object [-Werror,-Wobjc-property-no-attribute]
    4 errors generated.

* API/tests/testapi.mm: Default to (assign) for JSValue*
properties.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146712 268f45cc-cd09-0410-ab3c-d52691b4dbfc