Drop dependency on www/qt5-webkit.

Reduce qt5-assistant's dependency tree by dropping the dependency on QtWebKit.
Instead, use qt5-widgets' QTextBrowser to render documentation. An added bonus
is that with this change www/qt5-webengine no longer depends on www/qt5-webkit.

Page rendering is slightly worse, but everything is still very much readable.

Reviewed by:	tcberner
Differential Revision:	https://reviews.freebsd.org/D13630

devel/qt5-assistant/Makefile

@@ -2,13 +2,14 @@
 
 PORTNAME=	assistant
 DISTVERSION=	${QT5_VERSION}
+PORTREVISION=	1
 CATEGORIES=	devel
 PKGNAMEPREFIX=	qt5-
 
 MAINTAINER=	kde@FreeBSD.org
 COMMENT=	Qt 5 documentation browser
 
-USE_QT5=	core gui help network printsupport sql webkit widgets \
+USE_QT5=	core gui help network printsupport sql widgets \
 		buildtools_build sql-sqlite3_run
 QT_DIST=	tools
 USES=		qmake

devel/qt5-assistant/files/patch-src_assistant_assistant_assistant.pro

@@ -0,0 +1,13 @@
+Do not use QtWebKit even if it is present to reduce the port's dependencies.
+--- src/assistant/assistant/assistant.pro
++++ src/assistant/assistant/assistant.pro
+@@ -1,8 +1,4 @@
+-qtHaveModule(webkitwidgets):!contains(QT_CONFIG, static) {
+-    BROWSER = qtwebkit
+-} else {
+-    BROWSER = qtextbrowser
+-}
++BROWSER = qtextbrowser
+ 
+ QT += widgets network help sql help
+ qtHaveModule(printsupport): QT += printsupport