[turbofan] Simply context specialization and fix for OSR.

test/mjsunit/compiler/osr-block-scope.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 nest(body, name, depth) {
+  var header = "";
+  for (var i = 0; i < depth; i++) {
+    var x = "x" + (i + 1);
+    header += "  for(var " + x + " = 0; " + x + " < 2; " + x + " = " + x + " + 1 | 0) {\n";
+    body = body + "}"
+  }
+
+  return body.replace(new RegExp("function " + name + "\\(\\) {"),
+                      "function " + name + "_" + x + "() {\n" + header);
+}
+
+function test(expected, func, depth) {
+  assertEquals(expected, func());
+  assertEquals(expected, func());
+  assertEquals(expected, func());
+
+  var orig = func.toString();
+  var name = func.name;
+  for (var depth = 1; depth < 4; depth++) {
+    var body = nest(orig, name, depth);
+    func = eval("(" + body + ")");
+
+    assertEquals(expected, func());
+    assertEquals(expected, func());
+    assertEquals(expected, func());
+  }
+}
+
 function foo() {
   var result;
   {
     let sum = 0;
-    for (var i = 0; i < 100; i++) {
-      if (i == 50) %OptimizeOsr();
+    for (var i = 0; i < 10; i++) {
+      %OptimizeOsr();
       sum += i;
     }
     result = sum;
   }
   return result;
 }
 
-assertEquals(4950, foo());
-assertEquals(4950, foo());
-assertEquals(4950, foo());
+test(45, foo);
 
 function bar() {
-  var result;
+  let sum = 0;
+  for (var i = 0; i < 10; i++) {
+    %OptimizeOsr();
+    sum += i;
+  }
+  return sum;
+}
+
+test(45, bar);
+
+function bon() {
   {
     let sum = 0;
-    for (let i = 0; i < 90; i++) {
+    for (var i = 0; i < 10; i++) {
+      if (i == 5) %OptimizeOsr();
       sum += i;
-      if (i == 45) %OptimizeOsr();
     }
-    result = sum;
+    return sum;
+  }
+}
+
+test(45, bon);
+
+function row() {
+  var i = 0;
+  {
+    let sum = 0;
+    while (true) {
+      if (i == 8) return sum;
+      %OptimizeOsr();
+      sum = i;
+      i = i + 1 | 0;
+    }
+  }
+  return 11;
+}
+
+test(7, row);
+
+function nub() {
+  let i = 0;
+  while (i < 2) {
+    %OptimizeOsr();
+    i++;
+  }
+  return i;
+}
+
+test(2, nub);
+
+function kub() {
+  var result = 0;
+  let i = 0;
+  while (i < 2) {
+    let x = i;
+    %OptimizeOsr();
+    i++;
+    result = x;
   }
   return result;
 }
 
-assertEquals(4005, bar());
-assertEquals(4005, bar());
-assertEquals(4005, bar());
+test(1, kub);