Support column-based breakpoints in the VM and Observatory.

runtime/observatory/lib/src/service/object.dart

Index: runtime/observatory/lib/src/service/object.dart
diff --git a/runtime/observatory/lib/src/service/object.dart b/runtime/observatory/lib/src/service/object.dart
index cf244e4f427e61f878649d51958cf95c628e7584..8133ce1ff7845421e3dc4e972152f114afdf666b 100644
--- a/runtime/observatory/lib/src/service/object.dart
+++ b/runtime/observatory/lib/src/service/object.dart
@@ -432,6 +432,16 @@ class SourceLocation extends ServiceObject {
   int tokenPos;
   int endTokenPos;
 
+  Future<int> line() async {
+    await script.load();
+    return script.tokenToLine(tokenPos);
+  }
+
+  Future<int> column() async {
+    await script.load();
+    return script.tokenToCol(tokenPos);
+  }
+
   SourceLocation._empty(ServiceObject owner) : super._empty(owner);
 
   void _update(ObservableMap map, bool mapIsRef) {
@@ -1390,13 +1400,16 @@ class Isolate extends ServiceObjectOwner with Coverage {
     }
   }
 
-  Future<ServiceObject> addBreakpoint(Script script, int line) async {
+  Future<ServiceObject> addBreakpoint(Script script, int line, [int col]) async {
     // TODO(turnidge): Pass line as an int instead of a string.
     try {
       Map params = {
         'scriptId': script.id,
-        'line': '$line',
+        'line': line.toString(),
       };
+      if (col != null) {
+        params['column'] = col.toString();
+      }
       Breakpoint bpt = await invokeRpc('addBreakpoint', params);
       if (bpt.resolved &&
           script.loaded &&