Make copying from script insets omit line numbers and breakpoint indicators.

runtime/observatory/lib/src/elements/observatory_element.dart

Index: runtime/observatory/lib/src/elements/observatory_element.dart
diff --git a/runtime/observatory/lib/src/elements/observatory_element.dart b/runtime/observatory/lib/src/elements/observatory_element.dart
index f516bacbe6a214fd87b5d7c2a34f919e2b100636..8efc7b541936eefc5c2792bb339e30deade889f3 100644
--- a/runtime/observatory/lib/src/elements/observatory_element.dart
+++ b/runtime/observatory/lib/src/elements/observatory_element.dart
@@ -196,4 +196,35 @@ class ObservatoryElement extends PolymerElement {
     anchorElement.onClick.listen(onClickGoto);
     shadowRoot.children.add(anchorElement);
   }
+
+
+  var _onCopySubscription;
+  /// Exclude nodes from being copied, for example the line numbers and
+  /// breakpoint toggles in script insets. Must be called after [root]'s
+  /// children have been added, and only supports one node at a time.
+  void makeCssClassUncopyable(Element root, String className) {
+    var noCopyNodes = root.getElementsByClassName(className);
+    for (var node in noCopyNodes) {
+      node.style.setProperty('-moz-user-select', 'none');
+      node.style.setProperty('-khtml-user-select', 'none');
+      node.style.setProperty('-webkit-user-select', 'none');
+      node.style.setProperty('-ms-user-select', 'none');
+      node.style.setProperty('user-select', 'none');
+    }
+    if (_onCopySubscription != null) {
+      _onCopySubscription.cancel();
+    }
+    _onCopySubscription = root.onCopy.listen((event) {
+      // Mark the nodes as hidden before the copy happens, then mark them as
+      // visible on the next event loop turn.
+      for (var node in noCopyNodes) {
+        node.style.visibility = 'hidden';
+      }
+      Timer.run(() {
+        for (var node in noCopyNodes) {
+          node.style.visibility = 'visible';
+        }
+      });
+    });
+  }
 }