Revert "dart2js implementation of StringBuffer.writeAll that optimizes better."

sdk/lib/_internal/compiler/js_lib/core_patch.dart

Index: sdk/lib/_internal/compiler/js_lib/core_patch.dart
diff --git a/sdk/lib/_internal/compiler/js_lib/core_patch.dart b/sdk/lib/_internal/compiler/js_lib/core_patch.dart
index cca8f160a01ff847e8ad9a73bec5d0c6764cc57c..21be5acb8c48a9e23c2cfbca07fde3b7d32bc318 100644
--- a/sdk/lib/_internal/compiler/js_lib/core_patch.dart
+++ b/sdk/lib/_internal/compiler/js_lib/core_patch.dart
@@ -409,14 +409,8 @@ class StringBuffer {
     _writeString(new String.fromCharCode(charCode));
   }
 
-  @patch
-  void writeAll(Iterable objects, [String separator = ""]) {
-    _contents = _writeAll(_contents, objects, separator);
-  }
-
-  @patch
-  void writeln([Object obj = ""]) {
-    _writeString('$obj\n');
+  void _writeString(str) {
+    _contents = Primitives.stringConcatUnchecked(_contents, str);
   }
 
   @patch
@@ -426,31 +420,6 @@ class StringBuffer {
 
   @patch
   String toString() => Primitives.flattenString(_contents);
-
-  void _writeString(str) {
-    _contents = Primitives.stringConcatUnchecked(_contents, str);
-  }
-
-  static String _writeAll(String string, Iterable objects, String separator) {
-    Iterator iterator = objects.iterator;
-    if (!iterator.moveNext()) return string;
-    if (separator.isEmpty) {
-      do {
-        string = _writeOne(string, iterator.current);
-      } while (iterator.moveNext());
-    } else {
-      string = _writeOne(string, iterator.current);
-      while (iterator.moveNext()) {
-        string = _writeOne(string, separator);
-        string = _writeOne(string, iterator.current);
-      }
-    }
-    return string;
-  }
-
-  static String _writeOne(String string, Object obj) {
-    return Primitives.stringConcatUnchecked(string, '$obj');
-  }
 }
 
 @patch