Implement modular compilation

tool/input_sdk/private/ddc_runtime/utils.dart

Index: tool/input_sdk/private/ddc_runtime/utils.dart
diff --git a/tool/input_sdk/private/ddc_runtime/utils.dart b/tool/input_sdk/private/ddc_runtime/utils.dart
index a04c780a4f52035ca05c6e549b438b9c2bbce4ae..ac675feaca584e6ba5050f577e1c7fa9478069b0 100644
--- a/tool/input_sdk/private/ddc_runtime/utils.dart
+++ b/tool/input_sdk/private/ddc_runtime/utils.dart
@@ -100,16 +100,3 @@ copyTheseProperties(to, from, names) => JS('', '''(() => {
 copyProperties(to, from) => JS('', '''(() => {
   return $copyTheseProperties($to, $from, $getOwnNamesAndSymbols($from));
 })()''');
-
-/// Exports from one Dart module to another.
-@JSExportName('export')
-export_(to, from, show, hide) => JS('', '''(() => {
-  if ($show == void 0 || $show.length == 0) {
-    $show = $getOwnNamesAndSymbols($from);
-  }
-  if ($hide != void 0) {
-    var hideMap = new Set($hide);
-    $show = $show.filter((k) => !hideMap.has(k));
-  }
-  return $copyTheseProperties($to, $from, $show);
-})()''');