fixes for angular hello: String + and disable broken arg parsing

lib/runtime/dart/convert.js

 var convert;
 (function(exports) {
   'use strict';
   let ASCII = new AsciiCodec();
   let _ASCII_MASK = 127;
   let _allowInvalid = Symbol('_allowInvalid');
   let _nameToEncoding = Symbol('_nameToEncoding');
   let Codec$ = dart.generic(function(S, T) {
     class Codec extends core.Object {
       Codec() {
@@ skipping 1382 matching lines @@
   let _LF = Symbol('_LF');
   let _CR = Symbol('_CR');
   class _LineSplitterSink extends StringConversionSinkBase {
     _LineSplitterSink(sink$) {
       this[_sink] = sink$;
       this[_carry] = null;
       super.StringConversionSinkBase();
     }
     addSlice(chunk, start, end, isLast) {
       if (this[_carry] != null) {
-        chunk = core.String['+'](this[_carry], chunk.substring(start, end));
+        chunk = dart.notNull(this[_carry]) + dart.notNull(chunk.substring(start, end));
         start = 0;
         end = chunk.length;
         this[_carry] = null;
       }
       this[_carry] = _LineSplitterSink[_addSlice](chunk, start, end, isLast, this[_sink].add);
       if (isLast)
         this[_sink].close();
     }
     close() {
       this.addSlice('', 0, 0, true);
@@ skipping 1020 matching lines @@
   exports.LineSplitter = LineSplitter;
   exports.StringConversionSink = StringConversionSink;
   exports.ClosableStringSink = ClosableStringSink;
   exports.UNICODE_REPLACEMENT_CHARACTER_RUNE = UNICODE_REPLACEMENT_CHARACTER_RUNE;
   exports.UNICODE_BOM_CHARACTER_RUNE = UNICODE_BOM_CHARACTER_RUNE;
   exports.UTF8 = UTF8;
   exports.Utf8Codec = Utf8Codec;
   exports.Utf8Encoder = Utf8Encoder;
   exports.Utf8Decoder = Utf8Decoder;
 })(convert || (convert = {}));