Optimise scrollPage offset of browser.

core/browser.py

@@ -253,14 +253,13 @@ class WebHitTestResult():
             self.m_mediaUrl = data.mediaUrl().toString()
 
 def webview_scroll(webview, scroll_direction, scroll_type):
-    line_offset = 10
-    page_offset = 100
+    line_offset = 50
 
     if scroll_type == "page":
         if scroll_direction == "up":
-            webview.buffer_widget.web_page.runJavaScript("window.scrollBy({0}, {1});".format(0, page_offset));
+            webview.buffer_widget.web_page.runJavaScript("window.scrollBy(0, screen.height)");
         else:
-            webview.buffer_widget.web_page.runJavaScript("window.scrollBy({0}, {1});".format(0, -page_offset));
+            webview.buffer_widget.web_page.runJavaScript("window.scrollBy(0, -screen.height)");
     else:
         if scroll_direction == "up":
             webview.buffer_widget.web_page.runJavaScript("window.scrollBy({0}, {1});".format(0, line_offset));