Make Scanner::kNoSourcePos be a true sentinel value

runtime/vm/debugger.cc

 // Copyright (c) 2012, 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.
 
 #include "vm/debugger.h"
 
 #include "include/dart_api.h"
 
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
@@ skipping 75 matching lines @@
   ASSERT(!script.IsNull());
   ASSERT(token_pos_ >= 0);
 }
 
 // Create a latent breakpoint at given url and line number.
 BreakpointLocation::BreakpointLocation(const String& url,
                                        intptr_t requested_line_number,
                                        intptr_t requested_column_number)
     : script_(Script::null()),
       url_(url.raw()),
-      token_pos_(-1),
-      end_token_pos_(-1),
+      token_pos_(Scanner::kNoSourcePos),
+      end_token_pos_(Scanner::kNoSourcePos),
       is_resolved_(false),
       next_(NULL),
       conditions_(NULL),
       requested_line_number_(requested_line_number),
       requested_column_number_(requested_column_number),
       function_(Function::null()),
       line_number_(-1),
       column_number_(-1) {
   ASSERT(requested_line_number_ >= 0);
 }
@@ skipping 124 matching lines @@
     uword fp,
     uword sp,
     const Code& code,
     const Array& deopt_frame,
     intptr_t deopt_frame_offset)
     : pc_(pc), fp_(fp), sp_(sp),
       ctx_(Context::ZoneHandle()),
       code_(Code::ZoneHandle(code.raw())),
       function_(Function::ZoneHandle(code.function())),
       token_pos_initialized_(false),
-      token_pos_(-1),
+      token_pos_(Scanner::kNoSourcePos),
       try_index_(-1),
       line_number_(-1),
       column_number_(-1),
       context_level_(-1),
       deopt_frame_(Array::ZoneHandle(deopt_frame.raw())),
       deopt_frame_offset_(deopt_frame_offset),
       vars_initialized_(false),
       var_descriptors_(LocalVarDescriptors::ZoneHandle()),
       desc_indices_(8),
       pc_desc_(PcDescriptors::ZoneHandle()) {
@@ skipping 2990 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart