Added comments based on review feedback.

(cherry picked from commit 1d602f2)

Author: cwakamo

lib/Sema/PCMacro.cpp

@@ -287,6 +287,9 @@ class Instrumenter : InstrumenterBase {
 
   DeferStmt *transformDeferStmt(DeferStmt *DS) {
     if (auto *FD = DS->getTempDecl()) {
+      // Temporarily unmark the DeferStmt's FuncDecl as implicit so it is
+      // transformed (as typically implicit Decls are skipped by the
+      // transformer).
       auto Implicit = FD->isImplicit();
       FD->setImplicit(false);
       auto *D = transformDecl(FD);

lib/Sema/PlaygroundTransform.cpp

@@ -157,6 +157,9 @@ class Instrumenter : InstrumenterBase {
 
   DeferStmt *transformDeferStmt(DeferStmt *DS) {
     if (auto *FD = DS->getTempDecl()) {
+      // Temporarily unmark the DeferStmt's FuncDecl as implicit so it is
+      // transformed (as typically implicit Decls are skipped by the
+      // transformer).
       auto Implicit = FD->isImplicit();
       FD->setImplicit(false);
       auto *D = transformDecl(FD);