fixes #52, fields shadowing getters/setters or other fields

lib/runtime/dart/convert.js

Index: lib/runtime/dart/convert.js
diff --git a/lib/runtime/dart/convert.js b/lib/runtime/dart/convert.js
index 2447a47b7a79b8c30e3184b1293ba96d382e4493..e512334390949d2fee3b1355905cfc5cc71ef7cf 100644
--- a/lib/runtime/dart/convert.js
+++ b/lib/runtime/dart/convert.js
@@ -334,8 +334,8 @@ var convert;
       return this[_sink].close();
     }
   }
-  let _buffer = Symbol('_buffer');
   let _INITIAL_BUFFER_SIZE = Symbol('_INITIAL_BUFFER_SIZE');
+  let _buffer = Symbol('_buffer');
   let _callback = Symbol('_callback');
   let _bufferIndex = Symbol('_bufferIndex');
   let _roundToPowerOf2 = Symbol('_roundToPowerOf2');
@@ -498,11 +498,11 @@ var convert;
   let _name = Symbol('_name');
   class HtmlEscapeMode extends core.Object {
     [_](name, escapeLtGt, escapeQuot, escapeApos, escapeSlash) {
-      this[_name] = name;
-      this.escapeLtGt = escapeLtGt;
-      this.escapeQuot = escapeQuot;
-      this.escapeApos = escapeApos;
-      this.escapeSlash = escapeSlash;
+      dart.initField(HtmlEscapeMode, this, _name, name);
+      dart.initField(HtmlEscapeMode, this, 'escapeLtGt', escapeLtGt);
+      dart.initField(HtmlEscapeMode, this, 'escapeQuot', escapeQuot);
+      dart.initField(HtmlEscapeMode, this, 'escapeApos', escapeApos);
+      dart.initField(HtmlEscapeMode, this, 'escapeSlash', escapeSlash);
     }
     toString() {
       return this[_name];
@@ -517,7 +517,7 @@ var convert;
     HtmlEscape(mode) {
       if (mode === void 0)
         mode = HtmlEscapeMode.UNKNOWN;
-      this.mode = mode;
+      dart.initField(HtmlEscape, this, 'mode', mode);
       super.Converter();
     }
     convert(text) {
@@ -612,8 +612,8 @@ var convert;
   class JsonUnsupportedObjectError extends core.Error {
     JsonUnsupportedObjectError(unsupportedObject, opts) {
       let cause = opts && 'cause' in opts ? opts.cause : null;
-      this.unsupportedObject = unsupportedObject;
-      this.cause = cause;
+      dart.initField(JsonUnsupportedObjectError, this, 'unsupportedObject', unsupportedObject);
+      dart.initField(JsonUnsupportedObjectError, this, 'cause', cause);
       super.Error();
     }
     toString() {
@@ -681,14 +681,14 @@ var convert;
     JsonEncoder(toEncodable) {
       if (toEncodable === void 0)
         toEncodable = null;
-      this.indent = null;
+      dart.initField(JsonEncoder, this, 'indent', null);
       this[_toEncodable$] = toEncodable;
       super.Converter();
     }
     withIndent(indent, toEncodable) {
       if (toEncodable === void 0)
         toEncodable = null;
-      this.indent = indent;
+      dart.initField(JsonEncoder, this, 'indent', indent);
       this[_toEncodable$] = toEncodable;
       super.Converter();
     }