Add Vector type to Kernel

pkg/kernel/lib/type_algebra.dart

Index: pkg/kernel/lib/type_algebra.dart
diff --git a/pkg/kernel/lib/type_algebra.dart b/pkg/kernel/lib/type_algebra.dart
index ce4a553dc4a851e34e003d9e907e98002f8abd15..c86f4d21f80ec258cf0fa3dc8eb9806cad3c2852 100644
--- a/pkg/kernel/lib/type_algebra.dart
+++ b/pkg/kernel/lib/type_algebra.dart
@@ -365,6 +365,7 @@ abstract class _TypeSubstitutor extends DartTypeVisitor<DartType> {
   DartType visitDynamicType(DynamicType node) => node;
   DartType visitVoidType(VoidType node) => node;
   DartType visitBottomType(BottomType node) => node;
+  DartType visitVector(VectorType node) => node;
 
   DartType visitInterfaceType(InterfaceType node) {
     if (node.typeArguments.isEmpty) return node;
@@ -539,6 +540,7 @@ class _TypeUnification {
     if (type1 is VoidType && type2 is VoidType) return true;
     if (type1 is InvalidType && type2 is InvalidType) return true;
     if (type1 is BottomType && type2 is BottomType) return true;
+    if (type1 is VectorType && type2 is VectorType) return true;
     if (type1 is InterfaceType && type2 is InterfaceType) {
       if (type1.classNode != type2.classNode) return _fail();
       assert(type1.typeArguments.length == type2.typeArguments.length);
@@ -647,6 +649,7 @@ class _OccurrenceVisitor extends DartTypeVisitor<bool> {
   bool visitInvalidType(InvalidType node) => false;
   bool visitDynamicType(DynamicType node) => false;
   bool visitVoidType(VoidType node) => false;
+  bool visitVectorType(VectorType node) => false;
 
   bool visitInterfaceType(InterfaceType node) {
     return node.typeArguments.any(visit);