Add Vector type to Kernel

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

 library;
 import self as self;
 import "dart:core" as core;
-import "dart:mock" as mock;
 
 class C extends core::Object {
   field dynamic t;
   constructor foo(dynamic f) → void
-    : self::C::t = let final mock::Context #context = new mock::Context::•(1) in let dynamic #t1 = #context.[]=(0, f) in new self::Closure#C#foo#function::•(#context), super core::Object::•() {
-    final mock::Context #context = new mock::Context::•(1);
-    #context.[]=(0, f);
+    : self::C::t = let final Vector #context = MakeVector(2) in let dynamic #t1 = #context[1] = f in new self::Closure#C#foo#function::•(#context), super core::Object::•() {
+    final Vector #context = MakeVector(2);
+    #context[1] = f;
     core::print(1);
   }
 }
 class Closure#C#foo#function 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#C#foo#function::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#C#foo#function::context};
-    return #contextParameter.[](0).call();
+    final Vector #contextParameter = this.{self::Closure#C#foo#function::context};
+    return (#contextParameter[1]).call();
   }
 }
 class Closure#main#function 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#function::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#function::context};
+    final Vector #contextParameter = this.{self::Closure#main#function::context};
     return core::print("hest");
   }
 }
 static method main() → dynamic {
   core::print(0);
   dynamic c = new self::C::foo(new self::Closure#main#function::•(null));
   core::print(2);
   c.t();
   core::print(3);
 }