Implement type inference for symbol literals.

pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart

Index: pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
index c061dfe59df19447264edef3f8e4a2cadd9af02d..888ac72861037b12ec83b7b69920e59bf3741b38 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
@@ -1868,8 +1868,12 @@ class KernelSymbolLiteral extends SymbolLiteral implements KernelExpression {
   @override
   DartType _inferExpression(
       KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
-    // TODO(scheglov): implement.
-    return typeNeeded ? const DynamicType() : null;
+    typeNeeded =
+        inferrer.listener.symbolLiteralEnter(this, typeContext) || typeNeeded;
+    var inferredType =
+        typeNeeded ? inferrer.coreTypes.symbolClass.rawType : null;
+    inferrer.listener.symbolLiteralExit(this, inferredType);
+    return inferredType;
   }
 }