Fix a bug where breakpoints where not getting properly deleted.

runtime/observatory/tests/service/issue_25465_test.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// VMOptions=--error_on_bad_type --error_on_bad_override
+
+import 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+import 'test_helper.dart';
+import 'dart:async';
+
+testMain() {
+  var foo;      // line 11
+  foo = 42;     // line 12
+  print(foo);
+}
+
+var tests = [
+  hasPausedAtStart,
+
+  // Add breakpoints at line 11 and line 12.
+  (Isolate isolate) async {
+    var rootLib = isolate.rootLibrary;
+    await rootLib.load();
+    var script = rootLib.scripts[0];
+
+    var bpt1 = await isolate.addBreakpoint(script, 11);
+    var bpt2 = await isolate.addBreakpoint(script, 12);
+    expect(await bpt1.location.getLine(), equals(11));
+    expect(await bpt2.location.getLine(), equals(12));
+
+    var stream = await isolate.vm.getEventStream(VM.kDebugStream);
+    Completer completer = new Completer();
+    var subscription;
+    var breakCount = 0;
+    subscription = stream.listen((ServiceEvent event) async {
+      if (event.kind == ServiceEvent.kPauseBreakpoint) {
+        breakCount++;
+        print('break count is $breakCount');
+        if (breakCount == 1) {
+          // We are stopped at breakpoint 1.
+          expect(event.breakpoint.number, equals(bpt1.number));
+
+          // Remove both breakpoints
+          var result = await isolate.removeBreakpoint(bpt1);
+          expect(result.type, equals("Success"));
+
+          result = await isolate.removeBreakpoint(bpt2);
+          expect(result.type, equals("Success"));
+
+          isolate.stepOver();
+        } else {
+          // No breakpoint.
+          expect(event.breakpoint, isNull);
+
+          // We expect the next step to take us to line 12.
+          var stack = await isolate.getStack();
+          expect(await stack['frames'][0].location.getLine(), equals(12));
+
+          subscription.cancel();
+          completer.complete(null);
+        }
+      }
+    });
+    isolate.resume();
+    await completer.future;
+  },
+];
+
+main(args) => runIsolateTests(args, tests,
+                              testeeConcurrent: testMain,
+                              pause_on_start: true);