Activate emscripten with no-embedded option.

.travis.yml

@@ -128,7 +128,7 @@ install:
   - if [ "$PLATFORM" = "javascript" ]; then
       git clone --depth 1 "https://github.com/emscripten-core/emsdk.git";
       ./emsdk/emsdk install latest;
-      ./emsdk/emsdk activate latest;
+      ./emsdk/emsdk activate --no-embedded latest;
     fi
   - if [ "$STATIC_CHECKS" = "yes" ]; then
       unset SCONS_CACHE;