Fix wrong endianness of wasm header in WasmModuleWriter on big-endian platforms

src/wasm/encoder.cc

Index: src/wasm/encoder.cc
diff --git a/src/wasm/encoder.cc b/src/wasm/encoder.cc
index c563e22411033400e641dd4a882d9f0882d1e017..3a2015037e676f8056ba00f5ce47ba31f44f8d01 100644
--- a/src/wasm/encoder.cc
+++ b/src/wasm/encoder.cc
@@ -11,6 +11,7 @@
 #include "src/wasm/ast-decoder.h"
 #include "src/wasm/encoder.h"
 #include "src/wasm/leb-helper.h"
+#include "src/wasm/wasm-external-refs.h"
 #include "src/wasm/wasm-macro-gen.h"
 #include "src/wasm/wasm-module.h"
 #include "src/wasm/wasm-opcodes.h"
@@ -298,8 +299,8 @@ void WasmModuleWriter::WriteTo(ZoneBuffer& buffer) const {
 
   // == Emit magic =============================================================
   TRACE("emit magic\n");
-  buffer.write_u32(kWasmMagic);
-  buffer.write_u32(kWasmVersion);
+  buffer.write_u32(word32_to_little_endianness(&kWasmMagic));

[titzer, 2016/05/27 10:47:27]

What about instead making the write_u32 function always write little endian, and
forgoing the byte swap routines, similar to how the decoder always reads little
endian?

[ivica.bogosavljevic, 2016/05/27 12:23:24]

Say no more!

+  buffer.write_u32(word32_to_little_endianness(&kWasmVersion));
 
   // == Emit signatures ========================================================
   if (signatures_.size() > 0) {