Fix some egregious bugs in Var.

ppapi/tests/test_var.cc

Index: ppapi/tests/test_var.cc
===================================================================
--- ppapi/tests/test_var.cc	(revision 95308)
+++ ppapi/tests/test_var.cc	(working copy)
@@ -64,6 +64,13 @@
     ASSERT_EQ(NULL, result);
   }
 
+  // Make sure we can assign a C++ object to itself and it stays alive.
+  {
+    pp::Var a("test");
+    a = a;
+    ASSERT_TRUE(a.AsString() == "test");
+  }
+
   // Make sure nothing leaked.
   ASSERT_TRUE(testing_interface_->GetLiveObjectsForInstance(
       instance_->pp_instance()) == before_object);