Allow multiple client-side runtimes on a single page

Make XBlock client-side runtimes proper classes, so that handlerUrl can
be defined in a per-runtime way, and we can have multiple runtimes on a
single page.

[LMS-1630][LMS-1421][LMS-1517]

lms/djangoapps/instructor/views/instructor_dashboard.py

@@ -24,7 +24,6 @@ from django_comment_client.utils import has_forum_access
 from django_comment_common.models import FORUM_ROLE_ADMINISTRATOR
 from student.models import CourseEnrollment
 from bulk_email.models import CourseAuthorization
-from lms.lib.xblock.runtime import handler_prefix
 
 
 from .tools import get_units_with_due_date, title_or_url
@@ -206,7 +205,7 @@ def _section_send_email(course_id, access, course):
         ScopeIds(None, None, None, 'i4x://dummy_org/dummy_course/html/dummy_name')
     )
     fragment = course.system.render(html_module, 'studio_view')
-    fragment = wrap_xblock(partial(handler_prefix, course_id), html_module, 'studio_view', fragment, None)
+    fragment = wrap_xblock('LmsRuntime', html_module, 'studio_view', fragment, None, extra_data={"course-id": course_id})
     email_editor = fragment.content
     section_data = {
         'section_key': 'send_email',

lms/djangoapps/instructor/views/legacy.py

@@ -61,7 +61,6 @@ import track.views
 from xblock.field_data import DictFieldData
 from xblock.fields import ScopeIds
 from django.utils.translation import ugettext as _u
-from lms.lib.xblock.runtime import handler_prefix
 
 from microsite_configuration.middleware import MicrositeConfiguration
 
@@ -848,7 +847,7 @@ def instructor_dashboard(request, course_id):
             ScopeIds(None, None, None, 'i4x://dummy_org/dummy_course/html/dummy_name')
         )
         fragment = html_module.render('studio_view')
-        fragment = wrap_xblock(partial(handler_prefix, course_id), html_module, 'studio_view', fragment, None)
+        fragment = wrap_xblock('LmsRuntime', html_module, 'studio_view', fragment, None, extra_data={"course-id": course_id})
         email_editor = fragment.content
 
     # Enable instructor email only if the following conditions are met: