Fix epub export issue

Include the JS and CSS files in the Sphinx extension to make sure Sphinx
properly includes these when producing all output types.

Author: lkollar

Doc/library/profiling-sampling-visualization.html

@@ -1,3 +1 @@
-<link rel="stylesheet" href="../_static/profiling-sampling-visualization.css" />
 <div id="sampling-profiler-viz" class="sampling-profiler-viz"></div>
-<script src="../_static/profiling-sampling-visualization.js"></script>

Doc/tools/extensions/profiling_trace.py

@@ -156,6 +156,8 @@ def inject_trace(app, exception):
 
 def setup(app):
     app.connect('build-finished', inject_trace)
+    app.add_js_file('profiling-sampling-visualization.js')
+    app.add_css_file('profiling-sampling-visualization.css')
 
     return {
         'version': '1.0',