[debug] change coverage API to use offset instead of line/column.

src/inspector/js_protocol.json

Index: src/inspector/js_protocol.json
diff --git a/src/inspector/js_protocol.json b/src/inspector/js_protocol.json
index d8e18d6eceb3b15b30df063b22f41d28c6c0c93a..4237c45453b0400fa911daf22fbe5860296a557a 100644
--- a/src/inspector/js_protocol.json
+++ b/src/inspector/js_protocol.json
@@ -852,6 +852,8 @@
                     { "name": "startColumnNumber", "type": "integer", "description": "JavaScript script column number (0-based) for the range start." },
                     { "name": "endLineNumber", "type": "integer", "description": "JavaScript script line number (0-based) for the range end." },
                     { "name": "endColumnNumber", "type": "integer", "description": "JavaScript script column number (0-based) for the range end." },
+                    { "name": "startOffset", "type": "integer", "description": "JavaScript script source offset for the range start." },
+                    { "name": "endOffset", "type": "integer", "description": "JavaScript script source offset for the range end." },
                     { "name": "count", "type": "integer", "description": "Collected execution count of the source range." }
                 ],
                 "experimental": true