[FIX] web_editor: keep border when side style differ

Since e94702d8 when transcoding an element for the purpose of sending it
by mail, if the element had:

 border-bottom-style: solid;

in the CSS resulting from classes, it would be simplified to:

 border-style: 0 0 solid 0;

which is wrong since 0 is invalid for border-style, the default being:

 none

opw-1852839
closes #25423

addons/web_editor/static/src/js/editor/transcoder.js

@@ -108,9 +108,14 @@ function getMatchedCSSRules(a) {
     // The css generates all the attributes separately and not in simplified form.
     // In order to have a better compatibility (outlook for example) we simplify the css tags.
     // e.g. border-left-style: none; border-bottom-s .... will be simplified in border-style = none
-    _.each([['margin'], ['padding'], ['border', 'style']], function (attr) {
-        var p = attr[0];
-        var e = attr[1] ? '-' + attr[1] : '';
+    _.each([
+        {property: 'margin'},
+        {property: 'padding'},
+        {property: 'border', propertyEnd: '-style', defaultValue: 'none'},
+    ], function (propertyInfo) {
+        var p = propertyInfo.property;
+        var e = propertyInfo.propertyEnd || '';
+        var defVal = propertyInfo.defaultValue || 0;
 
         if (style[p+'-top'+e] || style[p+'-right'+e] || style[p+'-bottom'+e] || style[p+'-left'+e]) {
             if (style[p+'-top'+e] === style[p+'-right'+e] && style[p+'-top'+e] === style[p+'-bottom'+e] && style[p+'-top'+e] === style[p+'-left'+e]) {
@@ -119,7 +124,7 @@ function getMatchedCSSRules(a) {
             }
             else {
                 // keep => property: [top value] [right value] [bottom value] [left value];
-                style[p+e] = (style[p+'-top'+e] || 0) + ' ' + (style[p+'-right'+e] || 0) + ' ' + (style[p+'-bottom'+e] || 0) + ' ' + (style[p+'-left'+e] || 0);
+                style[p+e] = (style[p+'-top'+e] || defVal) + ' ' + (style[p+'-right'+e] || defVal) + ' ' + (style[p+'-bottom'+e] || defVal) + ' ' + (style[p+'-left'+e] || defVal);
                 if (style[p+e].indexOf('inherit') !== -1 || style[p+e].indexOf('initial') !== -1) {
                     // keep => property-top: [top value]; property-right: [right value]; property-bottom: [bottom value]; property-left: [left value];
                     delete style[p+e];