Add pointer check for NULL before dereference it.

Signed-off-by: sfu5
Reviewed-by: xdu2
Reviewed-by: ydong10


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12514 6f19259b-4bc3-4df7-8a09-765794883524

MdeModulePkg/Library/UefiHiiLib/HiiLib.c

@@ -2446,9 +2446,7 @@ InternalHiiGrowOpCodeHandle (
               OpCodeBuffer->BufferSize + (Size + HII_LIB_OPCODE_ALLOCATION_SIZE),
               OpCodeBuffer->Buffer
               );
-    if (Buffer == NULL) {
-      return NULL;
-    }
+    ASSERT (Buffer != NULL);
     OpCodeBuffer->Buffer = Buffer;
     OpCodeBuffer->BufferSize += (Size + HII_LIB_OPCODE_ALLOCATION_SIZE);
   }