[asmjs] Validator should reject modules with repeated functions.

src/typing-asm.cc

 // Copyright 2015 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.
 
 #include "src/typing-asm.h"
 
 #include <limits>
 
 #include "src/v8.h"
 
@@ skipping 148 matching lines @@
 }
 
 
 void AsmTyper::VisitFunctionDeclaration(FunctionDeclaration* decl) {
   if (in_function_) {
     FAIL(decl, "function declared inside another");
   }
   // Set function type so global references to functions have some type
   // (so they can give a more useful error).
   Variable* var = decl->proxy()->var();
+  if (GetVariableInfo(var)) {
+    // Detect previously-seen functions.
+    FAIL(decl->fun(), "function repeated in module");
+  }
   SetType(var, Type::Function());
 }
 
 
 void AsmTyper::VisitFunctionAnnotation(FunctionLiteral* fun) {
   // Extract result type.
   ZoneList<Statement*>* body = fun->body();
   Type* result_type = Type::Undefined();
   if (body->length() > 0) {
     ReturnStatement* stmt = body->last()->AsReturnStatement();
@@ skipping 1451 matching lines @@
 }
 
 
 void AsmTyper::VisitRewritableExpression(RewritableExpression* expr) {
   RECURSE(Visit(expr->expression()));
 }
 
 
 }  // namespace internal
 }  // namespace v8