Resubmit issue 2221103002 to fix the iOS build by declaring the flag in
SkCommonFlags.h

TBR=reed@google.com,caryclark@google.com

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2393643002

Review-Url: https://codereview.chromium.org/2393643002
diff --git a/dm/DM.cpp b/dm/DM.cpp
index 53709ba..c6e2ab9 100644
--- a/dm/DM.cpp
+++ b/dm/DM.cpp
@@ -34,6 +34,7 @@
 #include "Timer.h"
 #include "picture_utils.h"
 #include "sk_tool_utils.h"
+#include "SkScan.h"
 
 #ifdef SK_PDF_IMAGE_STATS
 extern void SkPDFImageDumpStats();
@@ -1274,6 +1275,10 @@
     setbuf(stdout, nullptr);
     setup_crash_handler();
 
+    if (FLAGS_analyticAA) {
+        GlobalAAConfig::getInstance().fUseAnalyticAA = true;
+    }
+
     if (FLAGS_verbose) {
         gVLog = stderr;
     } else if (!FLAGS_writePath.isEmpty()) {