[parser] Enhance debug prints: --print-scopes --print-ast

This makes it easier to match VariableProxys against variables in
Scopes (allocation-based prints such as local[0] or context[0] are not
unique).

R=vogelheim@chromium.org

Bug:

Change-Id: I8f86504f5e1657633286561e032805a8f6cff06e
Reviewed-on: https://chromium-review.googlesource.com/467486
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Daniel Vogelheim <vogelheim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44376}

src/ast/prettyprinter.cc

@@ -620,8 +620,8 @@ void AstPrinter::PrintLiteralWithModeIndented(const char* info,
     PrintLiteralIndented(info, value, true);
   } else {
     EmbeddedVector<char, 256> buf;
-    int pos =
-        SNPrintF(buf, "%s (mode = %s", info, VariableMode2String(var->mode()));
+    int pos = SNPrintF(buf, "%s (%p) (mode = %s", info, var,
+                       VariableMode2String(var->mode()));
     SNPrintF(buf + pos, ")");
     PrintLiteralIndented(buf.start(), value, true);
   }

src/ast/scopes.cc

@@ -1624,7 +1624,7 @@ void PrintVar(int indent, Variable* var) {
     PrintF(".%p", reinterpret_cast<void*>(var));
   else
     PrintName(var->raw_name());
-  PrintF(";  // ");
+  PrintF(";  // (%p) ", var);
   PrintLocation(var);
   bool comma = !var->IsUnallocated();
   if (var->has_forced_context_allocation()) {
@@ -1697,7 +1697,7 @@ void Scope::Print(int n) {
     function = AsDeclarationScope()->function_var();
   }
 
-  PrintF(" { // (%d, %d)\n", start_position(), end_position());
+  PrintF(" { // (%p) (%d, %d)\n", this, start_position(), end_position());
   if (is_hidden()) {
     Indent(n1, "// is hidden\n");
   }