Backport emscripten-core/emscripten#7631 for focus on iframes

[fdelapena]

Multiple games on sites like rmarchiv itch.io and similar will benefit on this.
Additinally, remove the default 'Downloading...' text to prevent user confusion when robots show web content preview.

Closes: #804.

[Ghabry]

looks fine but can't be tested right now because of EasyRPG/buildscripts#83

[fdelapena]

This is ready. Tested with Firefox and Chromium, automatic canvas resizing on windowed mode seems to work, though full screen toggle goes black for some (likely unrelated) reason.

[Ghabry]

Imo removing downloading is not the way to go. You could call it "Loading game..." and then use open graph standard to get a better link preview.

[fdelapena]

The "Downloading..." is set just later from JavaScript, so the experience doesn't change in practice. It could even contain a <noscript> there with meaningful Player details. Even the noscript gets overwritten from JS. Unfortunately not every preview out there uses open graph, including some search engines.

[Ghabry]

No idea how but your media queries (?) broke the fullscreen function.

You could also try with Module.requestFullscreen I replaced this with Module['canvas'].requestFullscreen because the emscripten solution was broken (it works by wrapping the canvas in a div and requesting fullscreen from the div)

[Ghabry]

There is this OBJECT_DEPENDS stuff in the CMake file where pre and post JS are specified. Just add the shell there and it will work

set_source_files_properties("src/main.cpp" PROPERTIES OBJECT_DEPENDS "${PLAYER_JS_PREJS};${PLAYER_JS_POSTJS};${PLAYER_JS_SHELL}")