[AIRFLOW-4294] Fix missing dag & task runs in UI dag_id contains a dot (

apache#5111)

We used to key on `safe_dag_id` but in that got changed in apache#4368 to use a 
more efficient query, which broke for non-sub-DAGs that contain a `.` in their id.

Arguably this escaping is a front-end concern anyway, so handling the escaping in the front end makes sense anyway.

airflow/www/templates/airflow/dags.html

@@ -312,7 +312,7 @@ <h2>DAGs</h2>
       d3.json("{{ url_for('airflow.dag_stats') }}", function(error, json) {
         for(var dag_id in json) {
             states = json[dag_id];
-            g = d3.select('svg#dag-run-' + dag_id)
+            g = d3.select('svg#dag-run-' + dag_id.replace(/\./g, '__dot__'))
               .attr('height', diameter + (stroke_width_hover * 2))
               .attr('width', '110px')
               .selectAll("g")
@@ -391,7 +391,7 @@ <h2>DAGs</h2>
       d3.json("{{ url_for('airflow.task_stats') }}", function(error, json) {
         for(var dag_id in json) {
             states = json[dag_id];
-            g = d3.select('svg#task-run-' + dag_id)
+            g = d3.select('svg#task-run-' + dag_id.replace(/\./g, '__dot__'))
               .attr('height', diameter + (stroke_width_hover * 2))
               .attr('width', '300px')
               .selectAll("g")