fix handling of justified spacers

these are new quads added the line so they need to observe the same line-height logic as the rest of the line. That means we don't just look at the line height of the line-quad prototype.

quad/quadwriter/line.rkt

@@ -82,6 +82,12 @@
     [(? string-quad?) (/ (quad-ref q :font-tracking 0) 2.0)]
     [_ 0]))
 
+(define (line-height-from-qs qs)
+  ;; line height is the max 'line-height value or the natural height of q:line
+  (match (filter-map (λ (q) (or (quad-ref q :line-height) (pt-y (size q)))) qs)
+    [(? null?) #false]
+    [line-heights (apply max line-heights)]))
+
 (define (fill-line-wrap all-qs line-prototype last-line-in-paragraph?)
   ;; happens during the finish of a line wrap, before consolidation of runs
   (unless (pair? all-qs)
@@ -134,12 +140,12 @@
               ;; which amounts to shrinking the word spaces till the line fits
               (and line-overfull? (> nonspacess-count 1))))
            (define justified-space-width (/ empty-hspace (sub1 nonspacess-count)))
-           (cons (make-left-edge-filler)
-                 (apply append (add-between hung-nonspacess (list (make-quad
+           (define justified-spacer (make-quad
                                      #:from 'bo
                                      #:to 'bi
                                      #:draw-end q:string-draw-end
-                                                                   #:size (pt justified-space-width line-prototype-height))))))]
+                                     #:size (pt justified-space-width (or (line-height-from-qs (append* hung-nonspacess)) line-prototype-height))))
+           (cons (make-left-edge-filler) (apply append (add-between hung-nonspacess (list justified-spacer))))]
           [else
            (define space-multiplier (match align-value
                                       ["center" 0.5]
@@ -200,10 +206,7 @@
                                (hash-ref! h :display default-block-id)
                                h)]
                       ;; line width is static
-                      ;; line height is the max 'line-height value or the natural height of q:line
-                      [size (pt line-width (match (filter-map (λ (q) (or (quad-ref q :line-height) (pt-y (size q)))) pcs)
-                                             [(? null?) line-height]
-                                             [line-heights (apply max line-heights)]))]
+                      [size (pt line-width (or (line-height-from-qs pcs) line-height))]
                       ;; handle list indexes. drop new quad into line to hold list index
                       ;; could also use this for line numbers
                       [elems