[runtime] Drop FIRST/LAST_NONCALLABLE_SPEC_OBJECT instance type range.

src/full-codegen/mips/full-codegen-mips.cc

Index: src/full-codegen/mips/full-codegen-mips.cc
diff --git a/src/full-codegen/mips/full-codegen-mips.cc b/src/full-codegen/mips/full-codegen-mips.cc
index 0d5cc7c9ec18ca46c38f58d6b0d46031c387041a..9bf1805d80f8a2b246c35740f507f0143237b20a 100644
--- a/src/full-codegen/mips/full-codegen-mips.cc
+++ b/src/full-codegen/mips/full-codegen-mips.cc
@@ -3316,22 +3316,14 @@ void FullCodeGenerator::EmitClassOf(CallRuntime* expr) {
 
   VisitForAccumulatorValue(args->at(0));
 
-  // If the object is a smi, we return null.
+  // If the object is not a JSReceiver, we return null.
   __ JumpIfSmi(v0, &null);
-
-  // Check that the object is a JS object but take special care of JS
-  // functions to make sure they have 'Function' as their class.
-  // Assume that there are only two callable types, and one of them is at
-  // either end of the type range for JS object types. Saves extra comparisons.
-  STATIC_ASSERT(NUM_OF_CALLABLE_SPEC_OBJECT_TYPES == 2);
+  STATIC_ASSERT(LAST_JS_RECEIVER_TYPE == LAST_TYPE);
   __ GetObjectType(v0, v0, a1);  // Map is now in v0.
   __ Branch(&null, lt, a1, Operand(FIRST_JS_RECEIVER_TYPE));
 
-  STATIC_ASSERT(LAST_NONCALLABLE_SPEC_OBJECT_TYPE ==
-                LAST_JS_RECEIVER_TYPE - 1);
-  __ Branch(&function, eq, a1, Operand(LAST_JS_RECEIVER_TYPE));
-  // Assume that there is no larger type.
-  STATIC_ASSERT(LAST_NONCALLABLE_SPEC_OBJECT_TYPE == LAST_TYPE - 1);
+  // Return 'Function' for JSFunction objects.
+  __ Branch(&function, eq, a1, Operand(JS_FUNCTION_TYPE));
 
   // Check if the constructor in the map is a JS function.
   Register instance_type = a2;