Type inference for StringConcatenation.

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 941b74f7df3529aee1664fc98ba330ead5116683..0e1d55b901314df7334db1fe0beee4abe8c5745d 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
@@ -500,8 +500,8 @@ class KernelStringConcatenation extends StringConcatenation
   @override
   DartType _inferExpression(
       KernelTypeInferrer inferrer, DartType typeContext, bool typeNeeded) {
-    // TODO(scheglov) Add and use inferStringConcatenation() instead.
-    return inferrer.inferStringLiteral(typeContext, typeNeeded);
+    return inferrer.inferStringConcatenation(
+        typeContext, typeNeeded, expressions);
   }
 }