[prettyprinter] improve call-printing of GetIterator nodes

Fix error message printed by Runtime_ThrowCalledNonCallable.

As noted on the bug, this has a slight problem in that it will always
print that "asyncIterator" was not callable for GetIterator with an
async IteratorType, though it may be referring to a different call.
This issue is present regardless of the change I introduced to perform
this desugaring in the BytecodeGenerator.

BUG=v8:6187
R=adamk@chromium.org, verwaest@chromium.org

Change-Id: I2077b7cd5976d9d9ba044f0dff44ee8c312d1263
Reviewed-on: https://chromium-review.googlesource.com/470806Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Cr-Commit-Position: refs/heads/master@{#44543}

src/ast/prettyprinter.cc

@@ -370,9 +370,18 @@ void CallPrinter::VisitEmptyParentheses(EmptyParentheses* node) {
 }
 
 void CallPrinter::VisitGetIterator(GetIterator* node) {
-  Print("GetIterator(");
+  // Because CallPrinter is used by RenderCallSite() in runtime-internal.cc,
+  // and the GetIterator node results in a Call, either to a [@@iterator] or
+  // [@@asyncIterator]. It's unknown which call this error refers to, so we
+  // assume it's the first call.
+  bool was_found = !found_ && node->position() == position_;
+  if (was_found) {
+    found_ = true;
+  }
   Find(node->iterable(), true);
-  Print(")");
+  Print(node->hint() == IteratorType::kNormal ? "[Symbol.iterator]"
+                                              : "[Symbol.asyncIterator]");
+  if (was_found) done_ = true;
 }
 
 void CallPrinter::VisitThisFunction(ThisFunction* node) {}

test/message/get-iterator1.js

+// Copyright 2017 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+function nonIterable() { return 0; }
+
+[...nonIterable()];

test/message/get-iterator1.out

+*%(basename)s:7: TypeError: nonIterable(...)[Symbol.iterator] is not a function
+[...nonIterable()];
+    ^
+TypeError: nonIterable(...)[Symbol.iterator] is not a function
+    at *%(basename)s:7:5