[inspector] allow negative line and column in Location

As long as we have scripts with negative source offset (see inline event listeners) we should not crash a browser when get negative offset.

R=jgruber@chromium.org

Bug: chromium:750592
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: Ic3138e7c61ec0a5133c56de9970acdffa5536d8e
Reviewed-on: https://chromium-review.googlesource.com/611613Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47318}

src/api.cc

@@ -9757,29 +9757,26 @@ debug::WasmDisassembly debug::WasmScript::DisassembleFunction(
 }
 
 debug::Location::Location(int line_number, int column_number)
-    : line_number_(line_number), column_number_(column_number) {
-  CHECK(line_number >= 0);
-  CHECK(column_number >= 0);
-}
+    : line_number_(line_number),
+      column_number_(column_number),
+      is_empty_(false) {}
 
 debug::Location::Location()
     : line_number_(v8::Function::kLineOffsetNotFound),
-      column_number_(v8::Function::kLineOffsetNotFound) {}
+      column_number_(v8::Function::kLineOffsetNotFound),
+      is_empty_(true) {}
 
 int debug::Location::GetLineNumber() const {
-  CHECK(line_number_ >= 0);
+  DCHECK(!IsEmpty());
   return line_number_;
 }
 
 int debug::Location::GetColumnNumber() const {
-  CHECK(column_number_ >= 0);
+  DCHECK(!IsEmpty());
   return column_number_;
 }
 
-bool debug::Location::IsEmpty() const {
-  return line_number_ == v8::Function::kLineOffsetNotFound &&
-         column_number_ == v8::Function::kLineOffsetNotFound;
-}
+bool debug::Location::IsEmpty() const { return is_empty_; }
 
 void debug::GetLoadedScripts(v8::Isolate* v8_isolate,
                              PersistentValueVector<debug::Script>& scripts) {

src/debug/interface-types.h

@@ -39,6 +39,7 @@ class V8_EXPORT_PRIVATE Location {
  private:
   int line_number_;
   int column_number_;
+  bool is_empty_;
 };
 
 /**

test/inspector/debugger/pause-at-negative-offset-expected.txt

+Tests that we dont crash on pause at negative offset
+(anonymous) (test.js:-3:-3)

test/inspector/debugger/pause-at-negative-offset.js

+// Copyright 2017 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.
+
+let {session, contextGroup, Protocol} =
+  InspectorTest.start('Tests that we dont crash on pause at negative offset');
+
+(async function test() {
+  session.setupScriptMap();
+  await Protocol.Debugger.enable();
+  contextGroup.addScript(`debugger;//# sourceURL=test.js`, -3, -3);
+  let {params:{callFrames}} = await Protocol.Debugger.oncePaused();
+  session.logCallFrames(callFrames);
+  InspectorTest.completeTest();
+})();