Reapply "Use CodeSourceMap for stack traces (still JIT only)."

runtime/vm/zone_text_buffer.h

+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#ifndef RUNTIME_VM_ZONE_TEXT_BUFFER_H_
+#define RUNTIME_VM_ZONE_TEXT_BUFFER_H_
+
+#include "vm/allocation.h"
+#include "vm/globals.h"
+
+namespace dart {
+
+class Zone;
+
+// TextBuffer maintains a dynamic character buffer with a printf-style way to
+// append text.
+class ZoneTextBuffer : ValueObject {
+ public:
+  ZoneTextBuffer(Zone* zone, intptr_t initial_capacity);
+  ~ZoneTextBuffer() {}
+
+  intptr_t Printf(const char* format, ...) PRINTF_ATTRIBUTE(2, 3);
+  void AddString(const char* s);
+
+  char* buffer() { return buffer_; }
+  intptr_t length() { return length_; }
+
+ private:
+  void EnsureCapacity(intptr_t len);
+  Zone* zone_;
+  char* buffer_;
+  intptr_t length_;
+  intptr_t capacity_;
+};
+
+}  // namespace dart
+
+#endif  // RUNTIME_VM_ZONE_TEXT_BUFFER_H_