Skip esvalid errors about unsupported node types

Esvalid https://github.com/estools/esvalid hasn't been updated for a
while, so it doesn't recognise newer JS standards' node types as valid
at all.

Rather than skip error checking altogether, I decided to just create a
list of all the node types esvalid supports, and ignore errors relating
to types other than those.  This way, we retain sanity checks for stuff
like variable names containing property access

    { type: "Identifier", name: "a.b" }

and other such insanity, which escodegen doesn't throw errors for for
performance reasons, but which are very likely to be user error.

Ideally in the long term we should patch esvalid to check new node types
for sanity also.

src/translate.ls

@@ -11,6 +11,26 @@ compile          = require \./compile
 
 { errors } = require \esvalid
 
+errors-about-nodes-esvalid-understands = do ->
+  # Ignore errors about nodes that esvalid can't currently handle.
+  (ast) ->
+    # This list is gathered from
+    # https://github.com/estools/esvalid/blob/2693f0906a3336de05d3325d10f8aa8297211bdb/index.js
+    # At time of writing, esvalid version is 1.1.0
+    esvalid-supported-node-types = <[
+      ArrayExpression AssignmentExpression BinaryExpression BlockStatement
+      BreakStatement CallExpression CatchClause ConditionalExpression
+      ContinueStatement DebuggerStatement DoWhileStatement EmptyStatement
+      ExpressionStatement ForInStatement ForStatement FunctionDeclaration
+      FunctionExpression Identifier IfStatement LabeledStatement Literal
+      LogicalExpression MemberExpression NewExpression ObjectExpression Program
+      ReturnStatement SequenceExpression SwitchCase SwitchStatement ThisExpression
+      ThrowStatement TryStatement UnaryExpression UpdateExpression
+      VariableDeclaration VariableDeclarator WhileStatement WithStatement
+    ]>
+    err = errors ast
+      .filter (.node.type in esvalid-supported-node-types)
+
 module.exports = (root-env, ast, options={}) ->
 
   transform-macros = (options.transform-macros || []) .map (func) ->
@@ -30,7 +50,7 @@ module.exports = (root-env, ast, options={}) ->
            |> (.filter (isnt null)) # because macro definitions emit null
            |> (.map statementify)
 
-  err = errors program-ast
+  err = errors-about-nodes-esvalid-understands program-ast
   if err.length
     first-error = err.0
     throw first-error

test.ls

@@ -1184,6 +1184,21 @@ test "macro can compile and return parameter as estree" ->
     '''
       ..`@equals` "3;\n'hi';\nc();\n({ a: b });"
 
+test "macro can handle new-ish JS features like ClassDeclaration" ->
+  esl '''
+    (macro test
+     (lambda ()
+      (return (object
+        "type" "ClassDeclaration"
+        "id" (object "type" "Identifier" "name" "A")
+        "superClass" null
+        "body" (object
+          "type" "ClassBody"
+          "body" (array))))))
+    (test)
+    '''
+      ..`@equals` "class A {\n}"
+
 test "multiple invocations of the compiler are separate" ->
   esl "(macro what (lambda () (return 'hi)))"
   esl "(what)"