[turbofan] Combine family of CallRuntime() methods into single imeplementation.

src/code-factory.h

 // Copyright 2012 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.
 
 #ifndef V8_CODE_FACTORY_H_
 #define V8_CODE_FACTORY_H_
 
 #include "src/allocation.h"
 #include "src/assembler.h"
 #include "src/codegen.h"
@@ skipping 12 matching lines @@
   Handle<Code> code() const { return code_; }
   CallInterfaceDescriptor descriptor() const { return descriptor_; }
 
  private:
   const Handle<Code> code_;
   const CallInterfaceDescriptor descriptor_;
 };
 
 class V8_EXPORT_PRIVATE CodeFactory final {
  public:
+  static Handle<Code> RuntimeCEntry(Isolate* isolate, int result_size = 1);

[Michael Starzinger, 2016/12/15 14:39:58]

Can we leave a comment here explaining that the {CEntryStub} has var-args
semantics ("argv" is passed on the stack and "argc" is passed via a register),
to explain the asymmetry why there is no CallInterfaceDescriptor available for
this "RuntimeCEntry" code.

+
   // Initial states for ICs.
   static Callable LoadIC(Isolate* isolate);
   static Callable LoadICInOptimizedCode(Isolate* isolate);
   static Callable LoadGlobalIC(Isolate* isolate, TypeofMode typeof_mode);
   static Callable LoadGlobalICInOptimizedCode(Isolate* isolate,
                                               TypeofMode typeof_mode);
   static Callable KeyedLoadIC(Isolate* isolate);
   static Callable KeyedLoadICInOptimizedCode(Isolate* isolate);
   static Callable KeyedLoadIC_Megamorphic(Isolate* isolate);
   static Callable CallIC(Isolate* isolate,
@@ skipping 129 matching lines @@
 
   static Callable ArrayPush(Isolate* isolate);
   static Callable FunctionPrototypeBind(Isolate* isolate);
   static Callable PromiseHandleReject(Isolate* isolate);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CODE_FACTORY_H_