Make Function.length and Function.name configurable properties.

test/mjsunit/regress/regress-1530.js

Index: test/mjsunit/regress/regress-1530.js
diff --git a/test/mjsunit/regress/regress-1530.js b/test/mjsunit/regress/regress-1530.js
index db2114450e4133371bc9045e0c409f5154333d01..6545900d176b4a4cd31d6b756d5a03af9b39f88f 100644
--- a/test/mjsunit/regress/regress-1530.js
+++ b/test/mjsunit/regress/regress-1530.js
@@ -62,8 +62,21 @@ assertSame(new f().foo, 'other');
 assertSame(Object.getPrototypeOf(new f()), z);
 assertSame(Object.getOwnPropertyDescriptor(f, 'prototype').value, z);
 
+// Verify that 'name' is (initially) non-writable, but configurable.
+var fname = f.name;
+f.name = z;
+assertSame(fname, f.name);
+Object.defineProperty(f, 'name', {value: 'other'});
+assertSame('other', f.name);
+
+// Verify same for 'length', another configurable and non-writable property.
+assertEquals(0, Object.getOwnPropertyDescriptor(f, 'length').value);
+assertDoesNotThrow(function () { Object.defineProperty(f, 'length', {writable: true}); });
+f.length = 3;
+assertEquals(3, Object.getOwnPropertyDescriptor(f, 'length').value);
+f.length = "untyped";
+assertSame("untyped", Object.getOwnPropertyDescriptor(f, 'length').value);
+
 // Verify that non-writability of other properties is respected.
-assertThrows("Object.defineProperty(f, 'name', { value: {} })");
-assertThrows("Object.defineProperty(f, 'length', { value: {} })");
 assertThrows("Object.defineProperty(f, 'caller', { value: {} })");
 assertThrows("Object.defineProperty(f, 'arguments', { value: {} })");