[ConstraintSystem] Minor refactor to avoid creating scopes we don't need.

This probably won't hit much, and shouldn't change behavior in any way
outside of statistics we generate about the number of scopes that get
opened.

Author: rudkx

lib/Sema/CSSolver.cpp

@@ -623,16 +623,15 @@ bool ConstraintSystem::tryTypeVariableBindings(
           << "\n";
       }
 
+      // If we were able to solve this without considering
+      // default literals, don't bother looking at default literals.
+      if (anySolved && binding.DefaultedProtocol && !sawFirstLiteralConstraint)
+        break;
+
       // Try to solve the system with typeVar := type
       ConstraintSystem::SolverScope scope(*this);
       if (binding.DefaultedProtocol) {
-        // If we were able to solve this without considering
-        // default literals, don't bother looking at default literals.
-        if (!sawFirstLiteralConstraint) {
-          sawFirstLiteralConstraint = true;
-          if (anySolved)
-            break;
-        }
+        sawFirstLiteralConstraint = true;
         type = openUnboundGenericType(type, typeVar->getImpl().getLocator());
         type = type->reconstituteSugar(/*recursive=*/false);
       } else if (binding.BindingSource == ConstraintKind::ArgumentConversion &&