Add optional FunctionType.positionalParameterNames and use them to resynthesize function-type forma…

runtime/vm/kernel_binary_flowgraph.cc

Index: runtime/vm/kernel_binary_flowgraph.cc
diff --git a/runtime/vm/kernel_binary_flowgraph.cc b/runtime/vm/kernel_binary_flowgraph.cc
index 34a20248b9bb9d8047dbf2d32c18c374395226b6..f66520cb7942d40d0a5923ed0184b6b6582815e0 100644
--- a/runtime/vm/kernel_binary_flowgraph.cc
+++ b/runtime/vm/kernel_binary_flowgraph.cc
@@ -1095,6 +1095,7 @@ void StreamingScopeBuilder::VisitFunctionType(bool simple) {
     }
   }
 
+  builder_->SkipListOfStrings();  // read positional parameter names.
   VisitDartType();  // read return type.
 }
 
@@ -1570,6 +1571,8 @@ void StreamingDartTypeTranslator::BuildFunctionType(bool simple) {
     }
   }
 
+  builder_->SkipListOfStrings();  // read positional parameter names.
+
   BuildTypeInternal();  // read return type.
   if (result_.IsMalformed()) {
     result_ = AbstractType::dynamic_type().raw();
@@ -3803,6 +3806,7 @@ void StreamingFlowGraphBuilder::SkipFunctionType(bool simple) {
     }
   }
 
+  SkipListOfStrings();  // read positional parameter names.
   SkipDartType();  // read return type.
 }
 
@@ -3820,6 +3824,13 @@ void StreamingFlowGraphBuilder::SkipListOfDartTypes() {
   }
 }
 
+void StreamingFlowGraphBuilder::SkipListOfStrings() {
+  intptr_t list_length = ReadListLength();  // read list length.
+  for (intptr_t i = 0; i < list_length; ++i) {
+    SkipStringReference();  // read ith string index.
+  }
+}
+
 void StreamingFlowGraphBuilder::SkipListOfVariableDeclarations() {
   intptr_t list_length = ReadListLength();  // read list length.
   for (intptr_t i = 0; i < list_length; ++i) {