Handle float in _convert_js_arg

This fixes 'gg' with QtWebEngine.

qutebrowser/utils/javascript.py

@@ -55,7 +55,7 @@ def _convert_js_arg(arg):
         return 'undefined'
     elif isinstance(arg, str):
         return '"{}"'.format(string_escape(arg))
-    elif isinstance(arg, int):
+    elif isinstance(arg, (int, float)):
         return str(arg)
     else:
         raise TypeError("Don't know how to handle {!r} of type {}!".format(

tests/unit/utils/test_javascript.py

@@ -126,6 +126,7 @@ class TestStringEscape:
     ('foobar', '"foobar"'),
     ('foo\\bar', r'"foo\\bar"'),
     (42, '42'),
+    (23.42, '23.42'),
     (None, 'undefined'),
     (object(), TypeError),
 ])