Pass a second type argument vector to all type instantiation calls in the VM.

runtime/vm/locations.h

Index: runtime/vm/locations.h
diff --git a/runtime/vm/locations.h b/runtime/vm/locations.h
index 249726438f3399db2c58dfa6418c2bf47b0b71d2..4a1778f9f52a9574a3f34875fb346f20296264df 100644
--- a/runtime/vm/locations.h
+++ b/runtime/vm/locations.h
@@ -552,7 +552,11 @@ class RegisterSet : public ValueObject {
 // Specification of locations for inputs and output.
 class LocationSummary : public ZoneAllocated {
  public:
-  enum ContainsCall { kNoCall, kCall, kCallOnSlowPath };
+  enum ContainsCall {
+    kNoCall,  // Used registers must be reserved as tmp.
+    kCall,    // Registers have been saved and can be used without reservation.
+    kCallOnSlowPath  // Used registers must be reserved as tmp.
+  };
 
   LocationSummary(Zone* zone,
                   intptr_t input_count,