Add Regex isCaseSensitive and isMultiLine to the service protocol and Observatory.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index d84a6209140f27ea2d3bf814c8ca7e5af2ce7494..c0b9241577e3d24ef7342da39158bf3b0c12fdb3 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -21128,6 +21128,9 @@ void JSRegExp::PrintJSONImpl(JSONStream* stream, bool ref) const {
     return;
   }
 
+  jsobj.AddProperty("isCaseSensitive", !is_ignore_case());
+  jsobj.AddProperty("isMultiLine", is_multi_line());
+
   Function& func = Function::Handle();
   func = function(kOneByteStringCid);
   jsobj.AddProperty("_oneByteFunction", func);