Implement type inference for assignments to a static variable.

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

Index: pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart b/pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart
index d7ce053a3fbce60ed23339bcc41263c3393f8695..8f95551f68b44cf4faafec308fe74bed292cf1a8 100644
--- a/pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/fasta_accessors.dart
@@ -9,6 +9,7 @@ import 'package:front_end/src/fasta/kernel/kernel_shadow_ast.dart'
         KernelArguments,
         KernelComplexAssignment,
         KernelIndexAssign,
+        KernelStaticAssignment,
         KernelThisExpression,
         KernelVariableAssignment;
 
@@ -708,6 +709,10 @@ class StaticAccessor extends kernel.StaticAccessor with FastaAccessor {
   }
 
   toString() => "StaticAccessor()";
+
+  @override
+  KernelComplexAssignment startComplexAssignment(Expression rhs) =>
+      new KernelStaticAssignment(rhs);
 }
 
 class SuperPropertyAccessor extends kernel.SuperPropertyAccessor