Phantom text (#1449)

* Enabling phantom in text mode.

* Adding screenshots.

src/functions/phantom.js

@@ -12,6 +12,7 @@ defineFunction({
     names: ["\\phantom"],
     props: {
         numArgs: 1,
+        allowedInText: true,
     },
     handler: ({parser}, args) => {
         const body = args[0];
@@ -42,6 +43,7 @@ defineFunction({
     names: ["\\hphantom"],
     props: {
         numArgs: 1,
+        allowedInText: true,
     },
     handler: ({parser}, args) => {
         const body = args[0];
@@ -84,6 +86,7 @@ defineFunction({
     names: ["\\vphantom"],
     props: {
         numArgs: 1,
+        allowedInText: true,
     },
     handler: ({parser}, args) => {
         const body = args[0];

test/screenshotter/ss_data.yaml

@@ -265,7 +265,10 @@ OverUnderset: |
     a+b+c+d\overset{b+c=0}\longrightarrow a+d\\
     \overset { x = y } { \sqrt { a b } }
     \end{array}
-Phantom: \dfrac{1+\phantom{x^{\blue{2}}} = x}{1+x^{\blue{2}} = x} \left(\vphantom{\int_t} zzz \right) \left( X \hphantom{\frac{\frac X X}{X}} \right)
+Phantom: \begin{array}{l}
+            \dfrac{1+\phantom{x^{\blue{2}}} = x}{1+x^{\blue{2}} = x} \left(\vphantom{\int_t} zzz \right) \left( X \hphantom{\frac{\frac X X}{X}} \right)\\
+            \text{a \phantom{123} b \hphantom{45678} c \vphantom{101112} d}
+         \end{array}
 PrimeSpacing: f'+f_2'+f^{f'}
 PrimeSuper: x'^2+x'''^2+x'^2_3+x_3'^2
 Raisebox: \frac{a}{a\raisebox{0.5em}{b}} \cdot \frac{a\raisebox{-0.5em}{b}}{a} \cdot \sqrt{a\raisebox{0.5em}{b}} \cdot \sqrt{a\raisebox{-0.5em}{b}} \cdot \sqrt{a\raisebox{0.5em}{b}\raisebox{-0.5em}{b}}