[epiphany] Use "-webkit-system-font" to obtain the system interface font in CSS

[Michael Catanzaro <mcatanzaro src gnome org>]

commit e53f2c0ec6d31c6c0008088a269003e911cb5af1
Author: Adrian Perez de Castro <aperez igalia com>
Date:   Wed Oct 18 00:36:02 2017 +0300

    Use "-webkit-system-font" to obtain the system interface font in CSS
    
    This replaces the "font: menu" CSS rules with "font-family: -webkit-system-font"
    ones. The latter are nicer to work with, because they only modify the font
    family without affecting the rest of the font attributes.
    
    Fixes bug #789119

 src/resources/about.css |    9 +++------
 src/resources/error.css |    3 +--
 2 files changed, 4 insertions(+), 8 deletions(-)
---
diff --git a/src/resources/about.css b/src/resources/about.css
index 23c7290..603039d 100644
--- a/src/resources/about.css
+++ b/src/resources/about.css
@@ -7,8 +7,7 @@ h1 {
 }
 
 html {
-        /* Pick system UI font and its properties, and then customize its size. */
-        font: menu;
+        font-family: -webkit-system-font, Cantarell, sans-serif;
         font-size: 11pt;
         color: #2e3436;
         padding: 20px 20px 0 20px;
@@ -233,8 +232,7 @@ html.epiphany-html {
     display: inline-block;
     margin-top: 10px;
     overflow: hidden;
-    /* Pick system UI font and its properties, and then customize its size. */
-    font: menu;
+    font-family: -webkit-system-font, Cantarell, sans-serif;
     font-size: 11pt;
     color: #2e3436;
     text-overflow: ellipsis;
@@ -270,8 +268,7 @@ html.epiphany-html {
     opacity: 0;
     z-index: 5;
     color: #888;
-    /* Pick system UI font and its properties, and then customize its size. */
-    font: menu;
+    font-family: -webkit-system-font, Cantarell, sans-serif;
     font-size: 14px;
     width: 13px;
     height: 14px;
diff --git a/src/resources/error.css b/src/resources/error.css
index aeab318..fdddb0c 100644
--- a/src/resources/error.css
+++ b/src/resources/error.css
@@ -1,8 +1,7 @@
 /* Global CSS for error pages */
 
 html {
-    /* Pick system UI font and its properties, and then customize its size. */
-    font: menu;
+    font-family: -webkit-system-font, Cantarell, sans-serif;
     font-size: 12pt;
     padding: 40px 20px 0 20px;
 }