[ASTGen] Make sure we spin the C++ parser even when we don't use it.

This is a temporary hack; we shouldn't even need to create the C++
parser here.

Author: DougGregor

lib/ASTGen/Sources/ASTGen/ASTGen.swift

@@ -70,7 +70,6 @@ public func parseTopLevelSwift(
     callback: @convention(c) (UnsafeMutableRawPointer, UnsafeMutableRawPointer) -> Void
 ) {
   let syntax = try! Parser.parse(source: String(cString: buffer))
-  dump(syntax)
   declContext = dc
   ASTGenVisitor(ctx: ctx, base: buffer)
     .visit(syntax)

lib/Parse/ParseDecl.cpp

@@ -190,6 +190,11 @@ void Parser::parseTopLevel(SmallVectorImpl<Decl *> &decls) {
       !SourceMgr.hasCodeCompletionBuffer() &&
       SF.Kind != SourceFileKind::SIL) {
     parseTopLevelSwift(contents.data(), CurDeclContext, &Context, &decls, appendToVector);
+
+    // Spin the C++ parser to the end; we won't be using it.
+    while (!Tok.is(tok::eof)) {
+      consumeToken();
+    }
     return;
   }
 #endif