Add readonly keyword in Obj-C / C++.

Author: SpartanJ

src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-c.cpp

@@ -135,7 +135,8 @@ SyntaxDefinition& addObjectiveC() {
 			  { "byref", "keyword" },
 			  { "in", "keyword" },
 			  { "out", "keyword" },
-			  { "inout", "keyword" } },
+			  { "inout", "keyword" },
+			  { "readonly", "keyword" } },
 
 		  "//",
 		  {}

src/modules/languages-syntax-highlighting/src/eepp/ui/doc/languages/objective-cpp.cpp

@@ -219,7 +219,8 @@ SyntaxDefinition& addObjectiveCPP() {
 			  { "byref", "keyword" },
 			  { "in", "keyword" },
 			  { "out", "keyword" },
-			  { "inout", "keyword" } },
+			  { "inout", "keyword" },
+			  { "readonly", "keyword" } },
 
 		  "//",
 		  {},