[wasm][asm.js] Forbid function declaration replacing variable declaration.

src/asmjs/asm-typer.cc

Index: src/asmjs/asm-typer.cc
diff --git a/src/asmjs/asm-typer.cc b/src/asmjs/asm-typer.cc
index 0ac40ec6f7ad73d0c30bc6ded3ba706e43a071dd..405047a5a29eb0aed8ccf32a1644b9bbb2fcf651 100644
--- a/src/asmjs/asm-typer.cc
+++ b/src/asmjs/asm-typer.cc
@@ -945,6 +945,10 @@ AsmType* AsmTyper::ExportType(VariableProxy* fun_export) {
     FAIL(fun_export, "Module export is not an asm.js function.");
   }
 
+  if (!fun_export->var()->is_function()) {
+    FAIL(fun_export, "Module exports must be function declarations.");
+  }
+
   return type;
 }