[turbofan] Optimize loads from the global object in JSTypeFeedbackSpecializer.

test/mjsunit/compiler/global-var-delete.js

Index: test/mjsunit/compiler/global-var-delete.js
diff --git a/test/mjsunit/compiler/global-var-delete.js b/test/mjsunit/compiler/global-var-delete.js
new file mode 100644
index 0000000000000000000000000000000000000000..a7ea9ea4b1145aaa859980b48c555c7a6bb8c9eb
--- /dev/null
+++ b/test/mjsunit/compiler/global-var-delete.js
@@ -0,0 +1,73 @@
+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+function test(expected, f) {
+  assertEquals(expected, f());
+  assertEquals(expected, f());
+  %OptimizeFunctionOnNextCall(f);
+  assertEquals(expected, f());
+  assertEquals(expected, f());
+}
+
+function testThrows(f) {
+  assertThrows(f);
+  assertThrows(f);
+  %OptimizeFunctionOnNextCall(f);
+  assertThrows(f);
+  assertThrows(f);
+}
+
+// --- Constant case.
+var a = 11;
+
+function f1() { return a; }
+test(11, f1);
+
+delete a;
+
+test(11, f1);
+
+
+// --- SMI case.
+
+var b = 11;
+b = 12;
+b = 13;
+
+function f2() { return b; }
+test(13, f2);
+
+delete b;
+
+test(13, f2);
+
+
+// --- double case.
+
+var c = 11;
+c = 12.25;
+c = 13.25;
+
+function f3() { return c; }
+test(13.25, f3);
+
+delete c;
+
+test(13.25, f3);
+
+
+// --- tagged case.
+
+var d = 11;
+d = 12.25;
+d = "hello";
+
+function f4() { return d; }
+test("hello", f4);
+
+delete d;
+
+test("hello", f4);