[observatory] Migrate off dart:html to package:web.

Remove use of svg, use unicode characters instead.
Run dart format on observatory sources.
Sort import statements with import_sorter.

No functional changes.

TEST=ci, manual
Change-Id: I7e4f67be06a27c8ab510ae8e50ce30b162780d30
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/426683
Commit-Queue: Alexander Aprelev <[email protected]>
Reviewed-by: Ryan Macnak <[email protected]>

Author: aam

runtime/observatory/bin/shell.dart

@@ -4,10 +4,10 @@
 
 library shell;
 
-import 'package:observatory/service_io.dart';
-
 import 'dart:io';
 
+import 'package:observatory/service_io.dart';
+
 // Simple demo for service_io library. Connects to localhost on the default
 // port, picks the first isolate, reads requests from stdin, and prints
 // results to stdout. Example session:

runtime/observatory/lib/app.dart

@@ -6,17 +6,21 @@ library app;
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:html';
+import 'dart:js_interop';
 
 import 'package:logging/logging.dart';
-import 'package:observatory/service_html.dart';
+import 'package:stack_trace/stack_trace.dart';
+import 'package:web/web.dart' as web;
+
 import 'package:observatory/elements.dart';
-import 'package:observatory/src/elements/helpers/uris.dart';
 import 'package:observatory/event.dart';
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/repositories.dart';
+import 'package:observatory/service_html.dart';
+import 'package:observatory/src/elements/helpers/element_utils.dart';
+import 'package:observatory/src/elements/helpers/uris.dart';
 import 'package:observatory/tracer.dart';
-import 'package:stack_trace/stack_trace.dart';
+import 'package:observatory/utils.dart';
 
 export 'package:observatory/utils.dart';
 

runtime/observatory/lib/debugger.dart

@@ -5,6 +5,7 @@
 library debugger;
 
 import 'dart:async';
+
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/service.dart';
 

runtime/observatory/lib/event.dart

@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:logging/logging.dart';
+
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/service.dart' as S;
 

runtime/observatory/lib/models.dart

@@ -5,6 +5,7 @@
 library models;
 
 import 'dart:async';
+
 import 'package:observatory/object_graph.dart';
 
 part 'src/models/exceptions.dart';

runtime/observatory/lib/repositories.dart

@@ -6,11 +6,13 @@ library repositories;
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:html';
+
+import 'package:web/web.dart';
+
 import 'package:observatory/allocation_profile.dart';
-import 'package:observatory/sample_profile.dart';
-import 'package:observatory/object_graph.dart';
 import 'package:observatory/models.dart' as M;
+import 'package:observatory/object_graph.dart';
+import 'package:observatory/sample_profile.dart';
 import 'package:observatory/service.dart' as S;
 import 'package:observatory/service_common.dart' as SC;
 import 'package:observatory/src/repositories/timeline_base.dart';

runtime/observatory/lib/sample_profile.dart

@@ -5,7 +5,9 @@
 library sample_profiler;
 
 import 'dart:async';
+
 import 'package:logging/logging.dart';
+
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/service.dart';
 import 'package:observatory/utils.dart';

runtime/observatory/lib/service.dart

@@ -6,10 +6,11 @@ library service;
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:typed_data';
 import 'dart:math' as math;
+import 'dart:typed_data';
 
 import 'package:logging/logging.dart';
+
 import 'package:observatory/event.dart' show createEventFromServiceEvent;
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/object_graph.dart';

runtime/observatory/lib/service_common.dart

@@ -9,6 +9,7 @@ import 'dart:convert';
 import 'dart:typed_data';
 
 import 'package:logging/logging.dart';
+
 import 'package:observatory/models.dart' as M;
 import 'package:observatory/service.dart';
 
@@ -60,7 +61,7 @@ class _WebSocketRequest {
       : completer = new Completer<Map>();
 }
 
-/// Minimal common interface for 'WebSocket' in [dart:io] and [dart:html].
+/// Minimal common interface for 'WebSocket' in [dart:io] and [package:web/web.dart].
 abstract class CommonWebSocket {
   Future<void> connect(WebSocketVMTarget target, void onOpen(),
       void onMessage(dynamic data), void onError(), void onClose());

runtime/observatory/lib/service_html.dart

@@ -5,9 +5,10 @@
 library service_html;
 
 import 'dart:async';
-import 'dart:html';
 import 'dart:typed_data';
 
+import 'package:web/web.dart';
+
 import 'package:observatory/service_common.dart';
 
 // Export the service library.
@@ -19,7 +20,7 @@ class _HtmlWebSocket implements CommonWebSocket {
   Future<void> connect(WebSocketVMTarget target, void onOpen(),
       void onMessage(dynamic data), void onError(), void onClose()) async {
     // The VM service will attempt to redirect our websocket connection request
-    // to DDS, but the dart:html WebSocket doesn't follow redirects. Instead of
+    // to DDS, but the package:web/web.dart WebSocket doesn't follow redirects. Instead of
     // relying on a redirect, we'll request the websocket URI from the service.
 
     // TODO(bkonyi): re-enable when DDS is enabled. Currently causing Observatory
@@ -63,7 +64,7 @@ class _HtmlWebSocket implements CommonWebSocket {
     FileReader fileReader = new FileReader();
     fileReader.readAsArrayBuffer(data);
     return fileReader.onLoadEnd.first.then((e) {
-      Uint8List result = fileReader.result as Uint8List;
+      final Uint8List result = (fileReader.result as ByteBuffer).asUint8List();
       return new ByteData.view(
           result.buffer, result.offsetInBytes, result.length);
     });