Add Vector type to Kernel

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

 library;
 import self as self;
 import "dart:core" as core;
-import "dart:mock" as mock;
 
 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 x) → 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};
-    return self::v = let final dynamic #t1 = #contextParameter in let final dynamic #t2 = 0 in let final dynamic #t3 = x in let final dynamic #t4 = #t1.[]=(#t2, #t3) in #t3;
+    final Vector #contextParameter = this.{self::Closure#main#function::context};
+    return self::v = #contextParameter[1] = x;
   }
 }
 class Closure#main#function#1 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#1::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#1::context};
-    for (; let final dynamic #t5 = #contextParameter in let final dynamic #t6 = 0 in let final dynamic #t7 = self::v in let final dynamic #t8 = #t5.[]=(#t6, #t7) in #t7; ) {
+    final Vector #contextParameter = this.{self::Closure#main#function#1::context};
+    for (; #contextParameter[1] = self::v; ) {
       self::v = false;
     }
   }
 }
 static field dynamic v = null;
 static method main(dynamic arguments) → dynamic {
-  final mock::Context #context = new mock::Context::•(1);
-  #context.[]=(0, null);
+  final Vector #context = MakeVector(2);
+  #context[1] = null;
   new self::Closure#main#function::•(#context).call(87);
   if(!self::v.==(87)) {
     throw "Unexpected value in v: ${self::v}";
   }
-  if(!#context.[](0).==(87)) {
-    throw "Unexpected value in w: ${#context.[](0)}";
+  if(!(#context[1]).==(87)) {
+    throw "Unexpected value in w: ${#context[1]}";
   }
   self::v = true;
   new self::Closure#main#function#1::•(#context).call();
   if(!self::v.==(false)) {
     throw "Unexpected value in v: ${self::v}";
   }
-  if(!#context.[](0).==(false)) {
-    throw "Unexpected value in w: ${#context.[](0)}";
+  if(!(#context[1]).==(false)) {
+    throw "Unexpected value in w: ${#context[1]}";
   }
 }