Support tab completion of line:col in the debugger.

runtime/observatory/tests/service/add_breakpoint_rpc_test.dart

Index: runtime/observatory/tests/service/add_breakpoint_rpc_test.dart
diff --git a/runtime/observatory/tests/service/add_breakpoint_rpc_test.dart b/runtime/observatory/tests/service/add_breakpoint_rpc_test.dart
index f1b3a1027899f63ab80d4729e055b1ea5864eaab..a51a2b3399a5cc3ad4793802044aa63bbbac8923 100644
--- a/runtime/observatory/tests/service/add_breakpoint_rpc_test.dart
+++ b/runtime/observatory/tests/service/add_breakpoint_rpc_test.dart
@@ -8,7 +8,6 @@ import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
 import 'deferred_library.dart' deferred as deferredLib;
 import 'dart:async';
-import 'dart:developer' as developer;
 
 int value = 0;
 
@@ -18,9 +17,9 @@ int incValue(int amount) {
 }
 
 Future testMain() async {
-  incValue(incValue(1));  // line 21
+  incValue(incValue(1));  // line 20
 
-  incValue(incValue(1));  // line 23
+  incValue(incValue(1));  // line 22
 
   await deferredLib.loadLibrary();
   deferredLib.deferredTest();
@@ -36,17 +35,17 @@ var tests = [
     var script = rootLib.scripts[0];
 
     // Future breakpoint.
-    var futureBpt1 = await isolate.addBreakpoint(script, 21);
+    var futureBpt1 = await isolate.addBreakpoint(script, 20);
     expect(futureBpt1.number, equals(1));
     expect(futureBpt1.resolved, isFalse);
-    expect(await futureBpt1.location.getLine(), equals(21));
+    expect(await futureBpt1.location.getLine(), equals(20));
     expect(await futureBpt1.location.getColumn(), equals(null));
 
     // Future breakpoint with specific column.
-    var futureBpt2 = await isolate.addBreakpoint(script, 21, 3);
+    var futureBpt2 = await isolate.addBreakpoint(script, 20, 3);
     expect(futureBpt2.number, equals(2));
     expect(futureBpt2.resolved, isFalse);
-    expect(await futureBpt2.location.getLine(), equals(21));
+    expect(await futureBpt2.location.getLine(), equals(20));
     expect(await futureBpt2.location.getColumn(), equals(3));
 
     var stream = await isolate.vm.getEventStream(VM.kDebugStream);
@@ -68,10 +67,10 @@ var tests = [
     // After resolution the breakpoints have assigned line & column.
     expect(resolvedCount, equals(2));
     expect(futureBpt1.resolved, isTrue);
-    expect(await futureBpt1.location.getLine(), equals(21));
+    expect(await futureBpt1.location.getLine(), equals(20));
     expect(await futureBpt1.location.getColumn(), equals(12));
     expect(futureBpt2.resolved, isTrue);
-    expect(await futureBpt2.location.getLine(), equals(21));
+    expect(await futureBpt2.location.getLine(), equals(20));
     expect(await futureBpt2.location.getColumn(), equals(3));
 
     // The first breakpoint hits before value is modified.
@@ -177,19 +176,19 @@ var tests = [
     var script = isolate.rootLibrary.scripts[0];
     // Try all columns, including some columns that are too big.
     for (int col = 1; col <= 50; col++) {
-      var bpt = await isolate.addBreakpoint(script, 21, col);
+      var bpt = await isolate.addBreakpoint(script, 20, col);
       expect(bpt.resolved, isTrue);
       int resolvedLine = await bpt.location.getLine();
       int resolvedCol = await bpt.location.getColumn();
-      print('21:${col} -> ${resolvedLine}:${resolvedCol}');
+      print('20:${col} -> ${resolvedLine}:${resolvedCol}');
       if (col <= 10) {
-        expect(resolvedLine, equals(21));
+        expect(resolvedLine, equals(20));
         expect(resolvedCol, equals(3));
       } else if (col <= 19) {
-        expect(resolvedLine, equals(21));
+        expect(resolvedLine, equals(20));
         expect(resolvedCol, equals(12));
       } else {
-        expect(resolvedLine, equals(23));
+        expect(resolvedLine, equals(22));
         expect(resolvedCol, equals(12));
       }
       expect((await isolate.removeBreakpoint(bpt)).type, equals('Success'));
@@ -198,7 +197,7 @@ var tests = [
     // Make sure that a zero column is an error.
     var caughtException = false;
     try {
-      await isolate.addBreakpoint(script, 21, 0);
+      await isolate.addBreakpoint(script, 20, 0);
       expect(false, isTrue, reason:'Unreachable');
     } on ServerRpcException catch(e) {
       caughtException = true;