Add comment about metadata syntax problem in static methods.

docs/language/dartLangSpec.tex

 \documentclass{article}
 \usepackage{epsfig}
 \usepackage{color}
 \usepackage{dart}
 \usepackage{bnf}
 \usepackage{hyperref}
 \usepackage{lmodern}
 \usepackage[T1]{fontenc}
 \newcommand{\code}[1]{{\sf #1}}
 \title{Dart Programming Language  Specification  \\
@@ skipping 892 matching lines @@
 {\bf mixins:}
   \WITH{} typeList
   .
 
 {\bf classMemberDefinition:}declaration `{\escapegrammar ;}' ;
        methodSignature functionBody
     .
 
 {\bf methodSignature:}constructorSignature initializers?;
       factoryConstructorSignature;
+% This doesn't work: `static @override foo() => 42`, but `functionSignature` starts with metadata. https://github.com/dart-lang/sdk/issues/29614
       \STATIC{}? functionSignature;
       \STATIC{}? getterSignature;
       \STATIC{}? setterSignature;
       operatorSignature
     .
 
 {\bf declaration:}constantConstructorSignature (redirection $|$ initializers)?;
       constructorSignature (redirection $|$ initializers)?;
       \EXTERNAL{} constantConstructorSignature;
       \EXTERNAL{} constructorSignature;
       ((\EXTERNAL{} \STATIC{}?))? getterSignature;
       ((\EXTERNAL{} \STATIC{}?))? setterSignature;
       \EXTERNAL{}? operatorSignature;
+% This doesn't work: `static @override foo() => 42`, but `functionSignature` starts with metadata. https://github.com/dart-lang/sdk/issues/29614
       ((\EXTERNAL{} \STATIC{}?))? functionSignature;
       \STATIC{} (\FINAL{} $|$ \CONST{}) type? staticFinalDeclarationList;
 %      \CONST{} type? staticFinalDeclarationList;
       \FINAL{} type? initializedIdentifierList;
       (\STATIC{} $|$ \COVARIANT{})? (\VAR{} $|$ type) initializedIdentifierList
     .
 
 {\bf staticFinalDeclarationList:}
     staticFinalDeclaration (`,' staticFinalDeclaration)*
     .
@@ skipping 7222 matching lines @@
 
 The invariant that each normative paragraph is associated with a line
 containing the text \LMHash{} should be maintained.  Extra occurrences
 of \LMHash{} can be added if needed, e.g., in order to make
 individual \item{}s in itemized lists addressable.  Each \LM.. command
 must occur on a separate line.  \LMHash{} must occur immediately
 before the associated paragraph, and \LMLabel must occur immediately
 after the associated \section{}, \subsection{} etc.
 
 ----------------------------------------------------------------------