Add graphql support, closes #298

after/syntax/javascript/graphql.vim

@@ -0,0 +1,27 @@
+if exists('g:polyglot_disabled') && index(g:polyglot_disabled, 'graphql') != -1
+  finish
+endif
+
+if exists('b:current_syntax')
+  let s:current_syntax = b:current_syntax
+  unlet b:current_syntax
+endif
+syn include @GraphQLSyntax syntax/graphql.vim
+if exists('s:current_syntax')
+  let b:current_syntax = s:current_syntax
+endif
+
+let s:tags = '\%(' . join(graphql#javascript_tags(), '\|') . '\)'
+
+exec 'syntax region graphqlTemplateString start=+' . s:tags . '\@20<=`+ skip=+\\`+ end=+`+ contains=@GraphQLSyntax,jsTemplateExpression,jsSpecial extend'
+exec 'syntax match graphqlTaggedTemplate +' . s:tags . '\ze`+ nextgroup=graphqlTemplateString'
+
+" Support expression interpolation ((${...})) inside template strings.
+syntax region graphqlTemplateExpression start=+${+ end=+}+ contained contains=jsTemplateExpression containedin=graphqlFold keepend
+
+hi def link graphqlTemplateString jsTemplateString
+hi def link graphqlTaggedTemplate jsTaggedTemplate
+hi def link graphqlTemplateExpression jsTemplateExpression
+
+syn cluster jsExpression add=graphqlTaggedTemplate
+syn cluster graphqlTaggedTemplate add=graphqlTemplateString