[turbofan] First shot at eager deoptimization in Turbofan.

test/mjsunit/compiler/eager-deopt-simple.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
 
-a = {y:1.5};
-a.y = 1093445778;
-b = a.y;
-c = {y:{}};
+function g(a, b, c) {
+  return a + b + c;
+}
 
 function f() {
-  return {y: b};
+  return g(1, (%DeoptimizeNow(), 2), 3);
 }
 
 f();
 f();
 %OptimizeFunctionOnNextCall(f);
-assertEquals(f().y, 1093445778);
+assertEquals(6, f());