[wasm][asm.js] Ignore duplicate exports in asm.js.

src/wasm/module-decoder.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/wasm/module-decoder.h"
 
 #include "src/base/functional.h"
 #include "src/base/platform/platform.h"
 #include "src/flags.h"
 #include "src/macro-assembler.h"
@@ skipping 473 matching lines @@
               }
               global->exported = true;
             }
             break;
           }
           default:
             error(pos, pos, "invalid export kind 0x%02x", exp->kind);
             break;
         }
       }
-      // Check for duplicate exports.
-      if (ok() && module->export_table.size() > 1) {
+      // Check for duplicate exports (except for asm.js).
+      if (ok() && origin_ != kAsmJsOrigin && module->export_table.size() > 1) {
         std::vector<WasmExport> sorted_exports(module->export_table);
         const byte* base = start_;
         auto cmp_less = [base](const WasmExport& a, const WasmExport& b) {
           // Return true if a < b.
           if (a.name_length != b.name_length) {
             return a.name_length < b.name_length;
           }
           return memcmp(base + a.name_offset, base + b.name_offset,
                         a.name_length) < 0;
         };
@@ skipping 726 matching lines @@
     table.push_back(std::move(func_asm_offsets));
   }
   if (decoder.more()) decoder.error("unexpected additional bytes");
 
   return decoder.toResult(std::move(table));
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8