Fix runtime clamp logic to match optimized code

tests/lib/typed_data/float32x4_clamp_test.dart

Index: tests/lib/typed_data/float32x4_clamp_test.dart
diff --git a/tests/lib/typed_data/float32x4_clamp_test.dart b/tests/lib/typed_data/float32x4_clamp_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..816fe0d5be63e113b59e1d60e5384af4e05b6443
--- /dev/null
+++ b/tests/lib/typed_data/float32x4_clamp_test.dart
@@ -0,0 +1,39 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// VMOptions=--optimization-counter-threshold=10
+
+// Library tag to be able to run in html test framework.
+library float32x4_clamp_test;
+
+import 'dart:typed_data';
+import 'package:expect/expect.dart';
+
+void testClampLowerGreaterThanUpper() {
+  Float32x4 l = new Float32x4(1.0, 1.0, 1.0, 1.0);
+  Float32x4 u = new Float32x4(-1.0, -1.0, -1.0, -1.0);
+  Float32x4 z = new Float32x4.zero();
+  Float32x4 a = z.clamp(l, u);
+  Expect.equals(a.x, 1.0);
+  Expect.equals(a.y, 1.0);
+  Expect.equals(a.z, 1.0);
+  Expect.equals(a.w, 1.0);
+}
+
+void testClamp() {
+  Float32x4 l = new Float32x4(-1.0, -1.0, -1.0, -1.0);
+  Float32x4 u = new Float32x4(1.0, 1.0, 1.0, 1.0);
+  Float32x4 z = new Float32x4.zero();
+  Float32x4 a = z.clamp(l, u);
+  Expect.equals(a.x, 0.0);
+  Expect.equals(a.y, 0.0);
+  Expect.equals(a.z, 0.0);
+  Expect.equals(a.w, 0.0);
+}
+
+main() {
+  for (int i = 0; i < 2000; i++) {
+    testClampLowerGreaterThanUpper();
+    testClamp();
+  }
+}