Reland of "Implement WASM big-endian support".

test/cctest/wasm/wasm-run-utils.h

Index: test/cctest/wasm/wasm-run-utils.h
diff --git a/test/cctest/wasm/wasm-run-utils.h b/test/cctest/wasm/wasm-run-utils.h
index 1f758bb8535dcf5ec316210a4a2b70829aa35aa9..0b4a5b8b81128075076e1e07c44d90ddb0bba548 100644
--- a/test/cctest/wasm/wasm-run-utils.h
+++ b/test/cctest/wasm/wasm-run-utils.h
@@ -139,14 +139,22 @@ class TestingModule : public ModuleEnv {
   template <typename T>
   T raw_mem_at(int i) {
     DCHECK(instance->mem_start);
-    return reinterpret_cast<T*>(instance->mem_start)[i];
+    return ReadMemory(&(reinterpret_cast<T*>(instance->mem_start)[i]));
   }
 
   template <typename T>
   T raw_val_at(int i) {
-    T val;
-    memcpy(&val, reinterpret_cast<void*>(instance->mem_start + i), sizeof(T));
-    return val;
+    return ReadMemory(reinterpret_cast<T*>(instance->mem_start + i));
+  }
+
+  template <typename T>
+  void WriteMemory(T* p, T val) {
+    WriteLittleEndianValue<T>(p, val);
+  }
+
+  template <typename T>
+  T ReadMemory(T* p) {
+    return ReadLittleEndianValue<T>(p);
   }
 
   // Zero-initialize the memory.