Enable native scrolling in all iOS versions newer than 5, not just iOS 6 (#12324)

Change-Id: I8f9ec7f34aefa5b48fd23f3f000f9455475edefa

WebContent/VAADIN/themes/base/common/common.scss

 	font-size: 0;
 	line-height: normal;
 }
-
-/* Enable kinetic scrolling on iOS 6 */
-.v-ios6.v-webkit & .v-scrollable {
+.v-ios.v-webkit & .v-scrollable {
 	-webkit-overflow-scrolling: touch; 
 }
+/* Disable native scrolling on iOS 5 due to #8792 */
+.v-ios5.v-webkit & .v-scrollable {
+	-webkit-overflow-scrolling: none;
+}
 
 &.v-overlay-container {
 	width: 0;

client/src/com/vaadin/client/BrowserInfo.java

             return prefix + OS_ANDROID;
         } else if (browserDetails.isIOS()) {
             String iosClass = prefix + OS_IOS;
-            if (isIOS6()) {
-                iosClass += " " + prefix + OS_IOS + "6";
+            if (getOperatingSystemMajorVersion() == 5) {
+                iosClass += " " + prefix + OS_IOS + "5";
             }
             return iosClass;
         } else if (browserDetails.isWindows()) {
         if (isAndroid() && isWebkit() && getWebkitVersion() >= 534) {
             return false;
         }
-        // iOS 6 Safari supports native scrolling; iOS 5 suffers from #8792
+        // iOS 6+ Safari supports native scrolling; iOS 5 suffers from #8792
         // TODO Should test other iOS browsers
-        if (isIOS6() && isWebkit()) {
+        if (isIOS() && isWebkit() && getOperatingSystemMajorVersion() >= 6) {
             return false;
         }
         return true;