Bug 110311

EFL and Qt use m_viewSize as a contents size while Apple use it as a viewport size, so EFL and Qt introduced m_viewportSize to make WebPage know a viewport size. EFL and Qt use m_viewSize as a contents size because the size of non compositing layer is contents size, and EFL and Qt mark whole non compositing layer as dirty using m_viewSize. Bug 110299 (http://webkit.org/b/110299) changes that it is not necessary to know m_viewSize when marking whole non compositing layer as dirty. So we can make EFL and Qt use m_viewSize as a viewport size also. This patch removes m_viewportSize and related methods to increase readability.