Bug 1236322 - Part 1: Annotate intentional switch fallthroughs to suppress -Wimplicit-fallthrough warnings in parser/. r=hsivonen

parser/html/nsHtml5Highlighter.cpp:572:9 [-Wimplicit-fallthrough] unannotated fall-through between switch labels

parser/htmlparser/nsScanner.cpp:425:7 [-Wimplicit-fallthrough] unannotated fall-through between switch labels
parser/htmlparser/nsScanner.cpp:780:7 [-Wimplicit-fallthrough] unannotated fall-through between switch labels

parser/html/nsHtml5Highlighter.cpp

@@ -9,6 +9,8 @@
 #include "nsString.h"
 #include "nsThreadUtils.h"
 #include "nsHtml5ViewSourceUtils.h"
+
+#include "mozilla/Attributes.h"
 #include "mozilla/Preferences.h"
 
 using namespace mozilla;
@@ -568,7 +570,7 @@ nsHtml5Highlighter::FlushChars()
           // the input data, because there are no reparses in the View Source
           // case, so we won't need the original data in the buffer anymore.
           buf[i] = '\n';
-          // fall through
+          MOZ_FALLTHROUGH;
         case '\n': {
           ++i;
           if (mCStart < i) {