Fix bugs in heapmap, binary payloads, 'address' request.

runtime/bin/vmservice/observatory/lib/service_html.dart

Index: runtime/bin/vmservice/observatory/lib/service_html.dart
===================================================================
--- runtime/bin/vmservice/observatory/lib/service_html.dart	(revision 42116)
+++ runtime/bin/vmservice/observatory/lib/service_html.dart	(working copy)
@@ -43,8 +43,12 @@
     assert(data is Blob);
     FileReader fileReader = new FileReader();
     fileReader.readAsArrayBuffer(data);
-    return fileReader.onLoadEnd.first.then((e)
-        => new ByteData.view(fileReader.result));
+    return fileReader.onLoadEnd.first.then((e) {
+      var result = fileReader.result;
+      return new ByteData.view(result.buffer,
+                               result.offsetInBytes,
+                               result.length);
+    });
   }
 }