Make wikitext editor use fonts consistent with rest of content

Monospace, serif, and sans-serif font stacks should all have consistent
metrics, so actually use them in wikitext editor. (Which depends on user
preferences.)
Also reset core font sizes added per T182320; that was done for skins
using system fonts elsewhere as well, and thus isn't really relevant here.

Also define out sans and serif font family variables independent of main
stack variables so they won't accidentally get overridden to other
things, but not presently following new naming conventions because
frankly I don't understand them and don't know which I should be using
to begin with. And even if I did, they're extremely long and we're
already exceeding maximum line length guidelines...

Bug: T247325
Change-Id: Iab98cfacab7dbc2f752bd200ee82d6d1a58c19a6

resources/forms.less

@@ -54,6 +54,26 @@ div.editOptions {
 	}
 }
 
+// Essentially revert T182320 (core change)
+// Custom font stacks below should fully address this issue regardless
+.mw-editfont-monospace,
+.mw-editfont-sans-serif,
+.mw-editfont-serif {
+	font-size: inherit;
+}
+
+.mw-editfont-monospace {
+	font-family: @fonts-mono;
+}
+
+.mw-editfont-sans-serif {
+	font-family: @fonts-sans;
+}
+
+.mw-editfont-serif {
+	font-family: @fonts-serif;
+}
+
 /* Extension:TemplateSandbox stuff */
 .mw-templatesandbox-page label {
 	padding: 0;

resources/themes/wikimedia.less

@@ -32,9 +32,12 @@
 // Flair
 
 // Fonts are chosen for consistent metrics, not necessarily overall prettiness.
-@fonts: 'Segoe UI', 'Segoe UI Emoji', 'Segoe UI Symbol', 'Lato', 'Liberation Sans', 'Noto Sans', 'Helvetica Neue', 'Helvetica', sans-serif;
-@fonts-secondary: 'Linux Libertine', 'Times New Roman', 'Liberation Serif', 'Nimbus Roman', 'Noto Serif', 'Times', serif;
+@fonts-sans: 'Segoe UI', 'Segoe UI Emoji', 'Segoe UI Symbol', 'Lato', 'Liberation Sans', 'Noto Sans', 'Helvetica Neue', 'Helvetica', sans-serif;
+@fonts-serif: 'Linux Libertine', 'Times New Roman', 'Liberation Serif', 'Nimbus Roman', 'Noto Serif', 'Times', serif;
 @fonts-mono: 'Menlo', 'Consolas', 'Monaco', 'Noto Mono', 'Nimbus Mono L', monospace;
 
+@fonts: @fonts-sans;
+@fonts-secondary: @fonts-serif;
+
 @border: 0.2em;
 @radius: 0.2em;