Merge pull request #12682 from overleaf/mj-def-whitespace

[lezer] Allow whitespace before macro parameter

GitOrigin-RevId: 14bd8428f0a78fb71184bf300dac0b2b1e3abd3c

services/web/frontend/js/features/source-editor/lezer-latex/latex.grammar

@@ -263,7 +263,7 @@ KnownCommand {
     } |
     Def {
         // allow more general Csname argument to \def commands, since other symbols such as '@' are often used in definitions
-        DefCtrlSeq (Csname | CtrlSym) MacroParameter* optionalWhitespace? DefinitionArgument
+        DefCtrlSeq (Csname | CtrlSym) optionalWhitespace? MacroParameter* optionalWhitespace? DefinitionArgument
     } |
     Hbox {
         HboxCtrlSeq optionalWhitespace? TextArgument