NO_PROXY support
Add NO_PROXY
-This resolves engine build failure:
| The compiler crashed: WebSocketException: Connection to 'http://127.0.0.1:39371/GAh-cZOn-eg=/ws#' was not upgraded t
o websocket
| #0 _WebSocketImpl.connect (dart:_http/websocket_impl.dart:1011:41)
| #1 WebSocket.connect (dart:_http/websocket.dart:320:22)
| #2 vmServiceConnectUri (package:vm_service/vm_service_io.dart:32:44)
| #3 _currentHeapCapacity (package:compiler/src/common/ram_usage.dart:27:41)
| <asynchronous suspension>
| #4 currentHeapCapacityInMb (package:compiler/src/common/ram_usage.dart:38:20)
| <asynchronous suspension>
| #5 compile.compilationDone (package:compiler/src/dart2js.dart:886:12)
| <asynchronous suspension>
| #6 main (package:compiler/src/dart2js.dart:1241:3)