[CSGen] NFC: Remove obsolete ConstraintSystem::{get, set}FavoredType

include/swift/Sema/ConstraintSystem.h

@@ -2211,10 +2211,6 @@ private:
 
   llvm::SetVector<TypeVariableType *> TypeVariables;
 
-  /// Maps expressions to types for choosing a favored overload
-  /// type in a disjunction constraint.
-  llvm::DenseMap<Expr *, TypeBase *> FavoredTypes;
-
   /// Maps discovered closures to their types inferred
   /// from declared parameters/result and body.
   ///
@@ -2955,15 +2951,6 @@ public:
     return nullptr;
   }
 
-  TypeBase* getFavoredType(Expr *E) {
-    assert(E != nullptr);
-    return this->FavoredTypes[E];
-  }
-  void setFavoredType(Expr *E, TypeBase *T) {
-    assert(E != nullptr);
-    this->FavoredTypes[E] = T;
-  }
-
   /// Set the type in our type map for the given node, and record the change
   /// in the trail.
   ///

lib/Sema/CSGen.cpp

@@ -403,7 +403,6 @@ namespace {
       Type fixedOutputType =
           CS.getFixedTypeRecursive(outputTy, /*wantRValue=*/false);
       if (!fixedOutputType->isTypeVariableOrMember()) {
-        CS.setFavoredType(anchor, fixedOutputType.getPointer());
         outputTy = fixedOutputType;
       }
 
@@ -807,11 +806,6 @@ namespace {
               return eltType;
             }
           }
-
-          if (!knownType->hasPlaceholder()) {
-            // Set the favored type for this expression to the known type.
-            CS.setFavoredType(E, knownType.getPointer());
-          }
         }
       }
 
@@ -1290,9 +1284,6 @@ namespace {
                               CS.getASTContext());
       }
 
-      if (auto favoredTy = CS.getFavoredType(expr->getSubExpr())) {
-        CS.setFavoredType(expr, favoredTy);
-      }
       return CS.getType(expr->getSubExpr());
     }
 
@@ -2567,7 +2558,6 @@ namespace {
       Type fixedType =
           CS.getFixedTypeRecursive(resultType, /*wantRvalue=*/true);
       if (!fixedType->isTypeVariableOrMember()) {
-        CS.setFavoredType(expr, fixedType.getPointer());
         resultType = fixedType;
       }