Revert of [intrinsic] Drop the %_ValueOf intrinsic.

src/full-codegen/x87/full-codegen-x87.cc

Index: src/full-codegen/x87/full-codegen-x87.cc
diff --git a/src/full-codegen/x87/full-codegen-x87.cc b/src/full-codegen/x87/full-codegen-x87.cc
index aa5b2bcba136fa1ef8c4ccf3b02fe1670d5984ae..147ee24cb0b8359359723169947465850018e259 100644
--- a/src/full-codegen/x87/full-codegen-x87.cc
+++ b/src/full-codegen/x87/full-codegen-x87.cc
@@ -2729,6 +2729,25 @@
   // All done.
   __ bind(&done);
 
+  context()->Plug(eax);
+}
+
+
+void FullCodeGenerator::EmitValueOf(CallRuntime* expr) {
+  ZoneList<Expression*>* args = expr->arguments();
+  DCHECK(args->length() == 1);
+
+  VisitForAccumulatorValue(args->at(0));  // Load the object.
+
+  Label done;
+  // If the object is a smi return the object.
+  __ JumpIfSmi(eax, &done, Label::kNear);
+  // If the object is not a value type, return the object.
+  __ CmpObjectType(eax, JS_VALUE_TYPE, ebx);
+  __ j(not_equal, &done, Label::kNear);
+  __ mov(eax, FieldOperand(eax, JSValue::kValueOffset));
+
+  __ bind(&done);
   context()->Plug(eax);
 }