Add Vector type to Kernel

pkg/kernel/testcases/closures/capture_closure_parameter.dart.expect

 library;
 import self as self;
 import "dart:core" as core;
-import "dart:mock" as mock;
 
 class Closure#main#foo#bar extends core::Object implements core::Function {
   field core::String note = "This is temporary. The VM doesn't need closure classes.";
-  field mock::Context context;
-  constructor •(final mock::Context context) → dynamic
+  field Vector context;
+  constructor •(final Vector context) → dynamic
     : self::Closure#main#foo#bar::context = context
     ;
   method call() → dynamic {
     "This is a temporary solution. In the VM, this will become an additional parameter.";
-    final mock::Context #contextParameter = this.{self::Closure#main#foo#bar::context};
-    core::print(#contextParameter.[](0));
+    final Vector #contextParameter = this.{self::Closure#main#foo#bar::context};
+    core::print(#contextParameter[1]);
   }
 }
 class Closure#main#foo extends core::Object implements core::Function {
   field core::String note = "This is temporary. The VM doesn't need closure classes.";
-  field mock::Context context;
-  constructor •(final mock::Context context) → dynamic
+  field Vector context;
+  constructor •(final Vector context) → dynamic
     : self::Closure#main#foo::context = context
     ;
   method call(dynamic x) → dynamic {
     "This is a temporary solution. In the VM, this will become an additional parameter.";
-    final mock::Context #contextParameter = this.{self::Closure#main#foo::context};
-    final mock::Context #context = new mock::Context::•(1);
-    #context.parent = #contextParameter;
-    #context.[]=(0, null);
+    final Vector #contextParameter = this.{self::Closure#main#foo::context};
+    final Vector #context = MakeVector(2);
+    #context[0] = #contextParameter;
+    #context[1] = null;
     final () → dynamic bar = new self::Closure#main#foo#bar::•(#context);
     return bar;
   }
 }
 static method main(core::List<core::String> arguments) → dynamic {
   final (dynamic) → dynamic foo = new self::Closure#main#foo::•(null);
   foo.call(arguments.[](0)).call();
 }