Realize IWYU pattern for handles.h header.

src/string-stream.h

 // Copyright 2014 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_STRING_STREAM_H_
 #define V8_STRING_STREAM_H_
 
+#include "src/allocation.h"
+#include "src/base/smart-pointers.h"
 #include "src/handles.h"
+#include "src/vector.h"
 
 namespace v8 {
 namespace internal {
 
+// Forward declarations.
+class ByteArray;
+
 class StringAllocator {
  public:
   virtual ~StringAllocator() { }
   // Allocate a number of bytes.
   virtual char* allocate(unsigned bytes) = 0;
   // Allocate a larger number of bytes and copy the old buffer to the new one.
   // bytes is an input and output parameter passing the old size of the buffer
   // and returning the new size.  If allocation fails then we return the old
   // buffer and do not increase the size.
   virtual char* grow(unsigned* bytes) = 0;
@@ skipping 145 matching lines @@
 
   bool full() const { return (capacity_ - length_) == 1; }
   int space() const { return capacity_ - length_; }
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(StringStream);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_STRING_STREAM_H_