Make blocks with 'overflow' different from 'visible' grow to include floating children.

Fix #661.

weasyprint/layout/blocks.py

@@ -638,6 +638,11 @@ def block_container_layout(context, box, max_position_y, skip_stack,
     # http://www.w3.org/TR/CSS21/visudet.html#normal-block
     # TODO: See float.float_layout
     if new_box.height == 'auto':
+        if context.excluded_shapes and new_box.style['overflow'] != 'visible':
+            max_float_position_y = max(
+                float_box.position_y + float_box.margin_height()
+                for float_box in context.excluded_shapes)
+            position_y = max(max_float_position_y, position_y)
         new_box.height = position_y - new_box.content_box_y()
 
     if new_box.style['position'] == 'relative':

weasyprint/tests/test_layout/test_block.py

@@ -705,3 +705,15 @@ def test_box_decoration_break_slice_bottom_padding():
     assert article.height == 20
     div, = article.children
     assert div.position_y == 0
+
+
+@assert_no_logs
+def test_overflow_auto():
+    page, = parse('''
+      <article style="overflow: auto">
+        <div style="float: left; height: 50px; margin: 10px">bla bla bla</div>
+          toto toto''')
+    html, = page.children
+    body, = html.children
+    article, = body.children
+    assert article.height == 50 + 10 + 10