[inspector] restore provisional breakpoints smarter

src/inspector/v8-debugger-script.h

Index: src/inspector/v8-debugger-script.h
diff --git a/src/inspector/v8-debugger-script.h b/src/inspector/v8-debugger-script.h
index 9250c9d87291a3dbe3771b43ff21d7991d409931..efb6995d15e24631ef6aecb6284cc6d88cfb2f0d 100644
--- a/src/inspector/v8-debugger-script.h
+++ b/src/inspector/v8-debugger-script.h
@@ -59,8 +59,8 @@ class V8DebuggerScript {
   bool hasSourceURL() const { return !m_sourceURL.isEmpty(); }
   const String16& sourceURL() const;
   virtual const String16& sourceMappingURL() const = 0;
-  virtual String16 source(v8::Isolate*) const { return m_source; }
-  const String16& hash(v8::Isolate*) const;
+  virtual String16 source() const { return m_source; }
+  const String16& hash() const;
   int startLine() const { return m_startLine; }
   int startColumn() const { return m_startColumn; }
   int endLine() const { return m_endLine; }
@@ -73,8 +73,11 @@ class V8DebuggerScript {
   virtual void setSourceMappingURL(const String16&) = 0;
   virtual void setSource(v8::Local<v8::String> source) {
     m_source = toProtocolString(source);
+    m_lineEndings.reset(nullptr);
   }
 
+  String16 lineAt(int lineNumberWithOffset, int maxLength);
+
   virtual bool getPossibleBreakpoints(
       const v8::debug::Location& start, const v8::debug::Location& end,
       std::vector<v8::debug::Location>* locations) = 0;
@@ -94,6 +97,8 @@ class V8DebuggerScript {
   int m_endColumn = 0;
   int m_executionContextId = 0;
 
+  std::unique_ptr<std::vector<size_t>> m_lineEndings;
+
   v8::Isolate* m_isolate;
 
  private: