[wasm] Passive data segments don't need a memory

This CL fixes a spec violation that new spec tests uncovered.

R=thibaudm@chromium.org
CC=ecmziegler@chromium.org

Change-Id: I1004eca9e4f98a0960795907fea0ab263c907938
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2122022Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66874}

src/wasm/module-decoder.cc

@@ -958,10 +958,6 @@ class ModuleDecoderImpl : public Decoder {
     module_->data_segments.reserve(data_segments_count);
     for (uint32_t i = 0; ok() && i < data_segments_count; ++i) {
       const byte* pos = pc();
-      if (!module_->has_memory) {
-        error("cannot load data without memory");
-        break;
-      }
       TRACE("DecodeDataSegment[%d] module+%d\n", i,
             static_cast<int>(pc_ - start_));
 
@@ -971,10 +967,16 @@ class ModuleDecoderImpl : public Decoder {
       consume_data_segment_header(&is_active, &memory_index, &dest_addr);
       if (failed()) break;
 
-      if (is_active && memory_index != 0) {
+      if (is_active) {
+        if (!module_->has_memory) {
+          error("cannot load data without memory");
+          break;
+        }
+        if (memory_index != 0) {
           errorf(pos, "illegal memory index %u != 0", memory_index);
           break;
         }
+      }
 
       uint32_t source_length = consume_u32v("source size");
       uint32_t source_offset = pc_offset();

test/mjsunit/wasm/bulk-memory.js

@@ -214,3 +214,11 @@ function getMemoryFill(mem) {
 
   assertEquals(0, view[0]);
 })();
+
+(function TestPassiveDataSegmentNoMemory() {
+  const builder = new WasmModuleBuilder();
+  builder.addPassiveDataSegment([0, 1, 2]);
+
+  // Should not throw.
+  builder.instantiate();
+})();