add more logging from ios simulator in verbose mode (flutter#4928)

Author: yjbanov

packages/flutter_tools/lib/src/ios/simulators.dart

@@ -786,6 +786,7 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
   String _lastLine;
 
   void _onDeviceLine(String line) {
+    printTrace('[DEVICE LOG] $line');
     Match multi = _lastMessageMultipleRegex.matchAsPrefix(line);
 
     if (multi != null) {
@@ -808,6 +809,7 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
   }
 
   void _onSystemLine(String line) {
+    printTrace('[SYS LOG] $line');
     if (!_flutterRunnerRegex.hasMatch(line))
       return;