Work around negative space bug in Chrome (#1194)

* Work around negative space bug in Chrome

Fix #984

The screenshot test is still somewhat defective, showing a space before
the "post" text (a period).  This seems limited to the screenshotter, however,
as it works fine in the tester via
http://localhost:7936/?text=%5Cfbox%7B%5C%241%2C%5C!000%2C%5C!000%7D%5CKaTeX&display=0&after=.

* Update screenshots

* Switch to inherited `width: min-content`

src/katex.less

@@ -25,6 +25,9 @@
     // Prevent a rendering bug that misplaces \vec in Chrome.
     text-rendering: auto;
 
+    // Fix width of containers of negative spaces, working around Chrome bug.
+    width: min-content;
+
     // Prevent background resetting on elements in Windows's high-contrast
     // mode, while still allowing background/foreground setting on root .katex
     * { -ms-high-contrast-adjust: none !important; }

test/screenshotter/ss_data.yaml

@@ -186,6 +186,9 @@ ModSpacing: |
         (a \cdot b) \mathbin{\mathrm{mod}} 257
     \end{array}
 NegativeSpaceBetweenRel: A =\!= B
+NegativeSpace:
+    tex: \fbox{\$1,\!000,\!000}\KaTeX
+    post: .
 NestedFractions: |
     \dfrac{\frac{a}{b}}{\frac{c}{d}}\dfrac{\dfrac{a}{b}}
     {\dfrac{c}{d}}\frac{\frac{a}{b}}{\frac{c}{d}}