[turbofan] Simply context specialization and fix for OSR.

test/mjsunit/compiler/osr-while-let.js

+// 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 --use-osr --turbo-osr
+
+"use strict";
+
+function test(expected, func) {
+  assertEquals(expected, func());
+  assertEquals(expected, func());
+  assertEquals(expected, func());
+}
+
+function foo() {
+  var result = 0;
+  {
+    let x = 0;
+    var temp_x = x;
+    var first = 1;
+    outer: while (true) {
+      let x = temp_x;
+      if (first == 1) first = 0;
+      else x = x + 1 | 0;
+      var flag = 1;
+      for (; flag == 1; (flag = 0, temp_x = x)) {
+        if (x < 2) {
+          result = x; %OptimizeOsr();
+        } else {
+          break outer;
+        }
+      }
+      if (flag == 1) break;
+    }
+  }
+  return result;
+}
+
+test(1, foo);
+
+
+function smo() {
+  var result = 0;
+  {
+    let x = 11;
+    outer: while (true) {
+      let y = x;
+      for (var i = 0; i < 5; i++) {
+        %OptimizeOsr();
+        if (i) break outer;
+        else result = y;
+      }
+    }
+  }
+  return result;
+}
+
+test(11, smo);