Revert "Retain types of toplevel and instance variables for reflection."

sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart

Index: sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart b/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
index b0e42eb6ebde5f0f65fae5fa6dc011e9c3f9ccd5..dd2d29390f529dcf3bdaf78c304fe10420138d57 100644
--- a/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart
@@ -137,14 +137,16 @@ class CodeEmitterTask extends CompilerTask {
     String reflectableField = namer.reflectableField;
 
     // function generateAccessor(field, prototype, cls) {
-    jsAst.Fun fun = js.fun(['fieldDescriptor', 'accessors', 'cls'], [
-      js('var fieldInformation = fieldDescriptor.split(":")'),
-      js('var field = fieldInformation[0]'),
+    jsAst.Fun fun = js.fun(['field', 'accessors', 'cls'], [
       js('var len = field.length'),
       js('var code = field.charCodeAt(len - 1)'),
-      js('var reflectable'),
-      js.if_('fieldInformation.length > 1', js('reflectable = true'),
-             js('reflectable = false')),
+      js('var reflectable = false'),
+      js.if_('code == $REFLECTION_MARKER', [
+          js('len--'),
+          js('code = field.charCodeAt(len - 1)'),
+          js('field = field.substring(0, len)'),
+          js('reflectable = true')
+      ]),
       js('code = ((code >= $RANGE1_FIRST) && (code <= $RANGE1_LAST))'
           '    ? code - $RANGE1_ADJUST'
           '    : ((code >= $RANGE2_FIRST) && (code <= $RANGE2_LAST))'