Implement graph trimming in ControlReducer.

test/mjsunit/asm/infinite-loops-taken.js

+// Copyright 2014 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.
+
+var error = "error";
+function counter(x) {
+  return (function() { if (x-- == 0) throw error;});
+}
+
+function Module() {
+  "use asm";
+
+  function w0(f) {
+    while (1) f();
+    return 108;
+  }
+
+  function w1(f) {
+    if (1) while (1) f();
+    return 109;
+  }
+
+  function w2(f) {
+    if (1) while (1) f();
+    else while (1) f();
+    return 110;
+  }
+
+  function w3(f) {
+    if (0) while (1) f();
+    return 111;
+  }
+
+  return { w0: w0, w1: w1, w2: w2, w3: w3 };
+}
+
+var m = Module();
+assertThrows(function() { m.w0(counter(5)) }, error);
+assertThrows(function() { m.w1(counter(5)) }, error);
+assertThrows(function() { m.w2(counter(5)) }, error);
+assertEquals(111, m.w3(counter(5)));