Update internals manual on how to add AST nodes.

StmtDumper.cpp is called ASTDumper.cpp these days, and usually works well
for new AST nodes without changes.  There's now DataRecursiveASTVisitor
in addition to RecursiveASTVisitor, and serialization wasn't mentioned.

llvm-svn: 212426

clang/docs/InternalsManual.rst

@@ -1852,13 +1852,14 @@ are similar.
    * Make sure that ``children()`` visits all of the subexpressions.  This is
      important for a number of features (e.g., IDE support, C++ variadic
      templates).  If you have sub-types, you'll also need to visit those
-     sub-types in the ``RecursiveASTVisitor``.
-   * Add printing support (``StmtPrinter.cpp``) and dumping support
-     (``StmtDumper.cpp``) for your expression.
+     sub-types in ``RecursiveASTVisitor`` and ``DataRecursiveASTVisitor``.
+   * Add printing support (``StmtPrinter.cpp``) for your expression.
    * Add profiling support (``StmtProfile.cpp``) for your AST node, noting the
      distinguishing (non-source location) characteristics of an instance of
      your expression.  Omitting this step will lead to hard-to-diagnose
      failures regarding matching of template declarations.
+   * Add serialization support (``ASTReaderStmt.cpp``, ``ASTWriterStmt.cpp``)
+     for your AST node.
 
 #. Teach semantic analysis to build your AST node.  At this point, you can wire
    up your ``Sema::BuildXXX`` function to actually create your AST.  A few