Bug 784739 - Switch from NULL to nullptr in layout/; r=ehsan

--HG--
extra : rebase_source : 0d0d9e11be9d39e4457bddd0bac7e19a50b91b0b
Bug 784739 - Switch from NULL to nullptr in widget/gtk/; r=ehsan

--HG--
extra : rebase_source : 538a634157e10b790b8278039101f2247ce37220
Bug 784739 - Switch from NULL to nullptr in widget/os2/; r=ehsan

--HG--
extra : rebase_source : c6afd8bd171364431280c8e69f406e36ebc5b523
Bug 784739 - Switch from NULL to nullptr in widget/windows/ (1/3); r=ehsan

--HG--
extra : rebase_source : 02a90b963833b2e9bf2938b32f401746730adf84
Bug 784739 - Switch from NULL to nullptr in widget/windows/ (2/3); r=ehsan

--HG--
extra : rebase_source : 5276b6474b9d6135ca2db408d17f0b5ed98b24a6
Bug 784739 - Switch from NULL to nullptr in widget/windows/ (3/3); r=ehsan

--HG--
extra : rebase_source : 5a2dc4df44ee396890b8b448580d4a04a4999899