Remove recently introduced FunctionType vm class by merging it into class Type.

runtime/vm/exceptions.cc

Index: runtime/vm/exceptions.cc
diff --git a/runtime/vm/exceptions.cc b/runtime/vm/exceptions.cc
index 654f7f63ca9eed5559408136c3310a9f5b4351f5..e2fa84e5de257b8ab4ce9ffa99bc395a877e3bc2 100644
--- a/runtime/vm/exceptions.cc
+++ b/runtime/vm/exceptions.cc
@@ -493,12 +493,24 @@ void Exceptions::CreateAndThrowTypeError(TokenPosition location,
         pieces.Add(Symbols::SingleQuote());
       }
       // Print URIs of src and dst types.
-      pieces.Add(Symbols::SpaceWhereNewLine());
+      // Do not print "where" when no URIs get printed.
+      bool printed_where = false;
       if (!src_type.IsNull()) {
-        pieces.Add(String::Handle(zone, src_type.EnumerateURIs()));
+        const String& uris = String::Handle(zone, src_type.EnumerateURIs());
+        if (uris.Length() > Symbols::SpaceIsFromSpace().Length()) {
+          printed_where = true;
+          pieces.Add(Symbols::SpaceWhereNewLine());
+          pieces.Add(uris);
+        }
       }
       if (!dst_type.IsDynamicType() && !dst_type.IsVoidType()) {
-        pieces.Add(String::Handle(zone, dst_type.EnumerateURIs()));
+        const String& uris = String::Handle(zone, dst_type.EnumerateURIs());
+        if (uris.Length() > Symbols::SpaceIsFromSpace().Length()) {
+          if (!printed_where) {
+            pieces.Add(Symbols::SpaceWhereNewLine());
+          }
+          pieces.Add(uris);
+        }
       }
     }
   }