X64 implementation: Emit correct merge code for virtual frames at CFG merges.

src/x64/codegen-x64.cc

Index: src/x64/codegen-x64.cc
===================================================================
--- src/x64/codegen-x64.cc	(revision 2231)
+++ src/x64/codegen-x64.cc	(working copy)
@@ -126,6 +126,16 @@
           "    }"
           "    return x;"
           "  }"
+          "\n"
+          "  function test_recursion_with_base(x, y, z, w) {"
+          "    if (x) {"
+          "     x = x;"
+          "    } else {"
+          "      x = test_recursion_with_base(y, z, w, 0);"
+          "    }"
+          "    return x;"
+          "  }"
+          "\n"
           "  function test_local_variables(x, y){"
           "    var w; y = x; x = w; w = y; y = x; return w;"
           "  };"
@@ -134,7 +144,8 @@
           "  test_local_variables("
           "      test_nesting_calls(test_local_variables(1,3), 42, 47),"
           "      test_local_variables(-25.3, 2));"
-          "  return test_if_then_else(1, 47, 39);"
+          "  return test_if_then_else(0, 46, 47);"
+          "  // return test_recursion_with_base(0, 0, 0, 47);\n"
           "})()")),
       Factory::NewStringFromAscii(CStrVector("CodeGeneratorTestScript")),
       0,