refactor(gui): drop setFullscreen now that chrome is a Lua node

Fullscreen was the firmware surrendering a strip it clipped apps out of.
The strip is a sibling node now, so an app that wants the panel is chrome
choosing not to build itself.

native/test/fake_providers.h

@@ -154,7 +154,6 @@ struct Fs : FsProvider {
 struct Gui : GuiProvider {
   std::string trace;
   int32_t degrees = 0;
-  bool fullscreen = false;
   bool gradient = false;
 
   FontIds fonts() const override {
@@ -195,7 +194,6 @@ struct Gui : GuiProvider {
     trace += border ? ",border" : ",-";
     trace += ");";
   }
-  void setFullscreen(bool on) override { fullscreen = on; }
   // Stands in for an e-ink panel, where a second commit is a second visible
   // refresh.
   void commit() override { commits++; }

native/test/runtime_test.cpp

@@ -129,12 +129,10 @@ int main() {
       "'confirm')");
   assert(bench.touch.calibration[3] == 400);
 
-  // Chrome control and gradients are core: an e-ink provider flattens what it
-  // cannot show.
-  run(state, "gui.setFullscreen(true)\n"
-             "gui.roundRect(0, 0, 10, 10, 4, 0, 0xFF, 0x00)\n"
+  // Gradients are core: an e-ink provider flattens what it cannot show.
+  run(state, "gui.roundRect(0, 0, 10, 10, 4, 0, 0xFF, 0x00)\n"
              "gui.roundRect(0, 0, 10, 10, 4, 0, nil, nil, 0xFF)");
-  assert(bench.gui.fullscreen && bench.gui.gradient);
+  assert(bench.gui.gradient);
   assert(bench.gui.trace.find("roundRect(-,border);") != std::string::npos);
 
   bench.gui.trace.clear();