Fix nasty off-by-one in the TurboFan JSON tracer.

src/compiler/pipeline.cc

 // 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.
 
 #include "src/compiler/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/base/platform/elapsed-timer.h"
@@ skipping 820 matching lines @@
       Handle<Script> script = info()->script();
       FunctionLiteral* function = info()->function();
       SmartArrayPointer<char> function_name =
           info()->shared_info()->DebugName()->ToCString();
       int pos = info()->shared_info()->start_position();
       json_of << "{\"function\":\"" << function_name.get()
               << "\", \"sourcePosition\":" << pos << ", \"source\":\"";
       if (!script->IsUndefined() && !script->source()->IsUndefined()) {
         DisallowHeapAllocation no_allocation;
         int start = function->start_position();
-        int len = function->end_position() - start + 1;
+        int len = function->end_position() - start;
         String::SubStringRange source(String::cast(script->source()), start,
                                       len);
         for (const auto& c : source) {
           json_of << AsEscapedUC16ForJSON(c);
         }
       }
       json_of << "\",\n\"phases\":[";
       fclose(json_file);
     }
   }
@@ skipping 324 matching lines @@
 
   if (FLAG_trace_turbo && !data->MayHaveUnverifiableGraph()) {
     TurboCfgFile tcf(data->isolate());
     tcf << AsC1VAllocator("CodeGen", data->register_allocator());
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8