[Constraint solver] No need to associate bound type variables everywhere.

When we are associating type variables with components in a “split” step,
there is no need to record already-bound type variables with every component.

(cherry picked from commit 0b61f86)

Author: DougGregor

lib/Sema/CSStep.cpp

@@ -164,12 +164,6 @@ void SplitterStep::computeFollowupSteps(
       componentSteps[known->second]->record(typeVar);
       continue;
     }
-
-    // Otherwise, associate it with all of the component steps,
-    // expect for components with orphaned constraints, they are
-    // not supposed to have any type variables.
-    for (unsigned i = 0; i != firstOrphanedComponent; ++i)
-      componentSteps[i]->record(typeVar);
   }
 
   // Transfer all of the constraints from the work list to