[Gardening] Tweaked comment.

Author: nate-chandler

lib/SILOptimizer/Mandatory/AddressLowering.cpp

@@ -1140,7 +1140,7 @@ bool OpaqueStorageAllocation::checkStorageDominates(
     }
     // Handle both phis and terminator results.
     auto *bbArg = cast<SILPhiArgument>(incomingValue);
-    // The storage block must strictly dominate the phi.
+    // The storage block must strictly dominate the argument block.
     if (!pass.domInfo->properlyDominates(allocInst->getParent(),
                                          bbArg->getParent())) {
       return false;

lib/SILOptimizer/Mandatory/AddressLowering.h

@@ -32,7 +32,7 @@ namespace swift {
 ///
 /// 4. Rewritten. The definition of this opaque value is fully translated
 /// into lowered SIL. Instructions are typically materialized and rewritten at
-/// the same time. A indirect result, however, is materialized as soon as its
+/// the same time. An indirect result, however, is materialized as soon as its
 /// alloc_stack is emitted, but only rewritten once the call itself is
 /// rewritten.
 ///