Add support for converted closures with explicit contexts to VM

runtime/vm/kernel_to_il.cc

Index: runtime/vm/kernel_to_il.cc
diff --git a/runtime/vm/kernel_to_il.cc b/runtime/vm/kernel_to_il.cc
index b5dfb9882f3b588550b0fc7898d480744df31e78..bfa7743885e4a8fa5e6f9b3da7147297418bd1db 100644
--- a/runtime/vm/kernel_to_il.cc
+++ b/runtime/vm/kernel_to_il.cc
@@ -844,7 +844,7 @@ Fragment FlowGraphBuilder::TranslateInstantiatedTypeArguments(
   return instructions;
 }
 
-Fragment FlowGraphBuilder::AllocateContext(int size) {
+Fragment FlowGraphBuilder::AllocateContext(intptr_t size) {
   AllocateContextInstr* allocate =
       new (Z) AllocateContextInstr(TokenPosition::kNoSource, size);
   Push(allocate);