Get rid of the different kinds of yield in the AST & full-codegen.

src/ast/prettyprinter.cc

Index: src/ast/prettyprinter.cc
diff --git a/src/ast/prettyprinter.cc b/src/ast/prettyprinter.cc
index 0e9986a438166effbd55f2eb54ae9fa2d7f3f02e..158221f04a930306ebb742598bbf9f32d16d3b68 100644
--- a/src/ast/prettyprinter.cc
+++ b/src/ast/prettyprinter.cc
@@ -1593,9 +1593,7 @@ void AstPrinter::VisitAssignment(Assignment* node) {
 
 
 void AstPrinter::VisitYield(Yield* node) {
-  EmbeddedVector<char, 128> buf;
-  SNPrintF(buf, "YIELD (kind %d)", node->yield_kind());
-  IndentedScope indent(this, buf.start(), node->position());
+  IndentedScope indent(this, "YIELD", node->position());
   Visit(node->expression());
 }