[parsing] When failing due to variable redeclaration, point at the variable.

src/parsing/parser.h

Index: src/parsing/parser.h
diff --git a/src/parsing/parser.h b/src/parsing/parser.h
index 37dc0d8a6754ed2efa0eb386c7200ce8e6517421..7344d26d42a20b6024d6fa2f664feb95d62c3a12 100644
--- a/src/parsing/parser.h
+++ b/src/parsing/parser.h
@@ -468,7 +468,7 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
   Variable* Declare(Declaration* declaration,
                     DeclarationDescriptor::Kind declaration_kind,
                     VariableMode mode, InitializationFlag init, bool* ok,
-                    Scope* declaration_scope = nullptr);
+                    Scope* declaration_scope = nullptr, int var_end_pos = -1);

[adamk, 2016/10/27 10:32:49]

kNoSourcePosition

   Declaration* DeclareVariable(const AstRawString* name, VariableMode mode,
                                int pos, bool* ok);
   Declaration* DeclareVariable(const AstRawString* name, VariableMode mode,