Pass a JSContext to JSValConvertible::from_jsval.
Reimplement conversion to primitive types for correctness in the face of non-primitive arguments.
Implement `position: absolute` for non-replaced elements.

+ Re-implement fixed positioning using the absolute positioning code.
+ Add reftests for absolute positioning and fixed positioning.
+ Refactor assign_widths in BlockFlow to isolate the calculation of
widths and margins.
+ Pass down details of the Containing Block for absolute and fixed flows
during layout. Use it to calculate the static position of absolute flows.
+ Defer calculation of absolute flow dimensions till we build the
display list.
Implement mini-traversal for absolute flow assign-height.

This only traverses absolute flows, nothing else.

+ Also, a separate mini-traversal for store overflow.
+ Store descendants with position 'absolute' and 'fixed' in BaseFlow.
+ Bubble up links to absolute and fixed descendants during Flow Construction.
+ Set Rawlink to the CB in absolute descendants.
+ store_overflow() now uses absolute descendants' overflows too.
+ Add reftests for 'absolute' and 'fixed' static y position.
+ Add reftests for overflow (they all fail now).
+ Put absolute flow display items under their CB's ClipDisplayItem.
+ Paint borders in Box_ before the actual box stuff (minor fix in lieu of paint-order).
Remove unused argument to CreateInterfaceObjects2.
Remove unused argument to CreateInterfaceObject and now unused code.
auto merge of #1795 : Ms2ger/servo/CreateInterfaceObject, r=jdm
Fix test.
auto merge of #1791 : Ms2ger/servo/conversions, r=jdm
auto merge of #1681 : pradeep90/servo/absolute-position, r=pcwalton

+ Re-implement fixed positioning using the absolute positioning code.
+ Add reftests for absolute positioning and fixed positioning.
+ Refactor assign_widths in BlockFlow to isolate the calculation of
widths and margins.
+ Pass down details of the Containing Block for absolute and fixed flows
during layout. Use it to calculate the static position of absolute flows.
+ Defer calculation of absolute flow dimensions till we build the
display list.

This implements https://github.com/mozilla/servo/issues/1537 and https://github.com/mozilla/servo/issues/787
Don't build Fontconfig docs

Fixes #1790
Remove support for external (i.e. XPIDL) interfaces.
auto merge of #1796 : kmcallister/servo/linux-fontconfig, r=jdm

Fixes #1790

r? @jdm
auto merge of #1797 : Ms2ger/servo/IDL-debris, r=jdm
Fix Android argument handling

Copy-paste fail from my c277d25506b61a34a3b28dcf4433e203ffa43284
auto merge of #1798 : kmcallister/servo/android-args, r=jdm

Copy-paste fail from my c277d25506b61a34a3b28dcf4433e203ffa43284

r? @jdm
Fix a dynamic borrow failure with iframes
auto merge of #1800 : kmcallister/servo/subpage-id, r=jdm
Remove next_subpage_id argument from parse_html.(fixes #1801)
auto merge of #1802 : lpy/servo/issue1801, r=kmcallister

see #1801