Use default export templates for HTML5

Changes Emscripten SDK version to match that used to compile the default export
templates used by Godot 3.5 (in this case 3.1.14 as can be seen here:
https://github.com/godotengine/build-containers/blob/3.5/Dockerfile.javascript).

This means we no longer need to compile custom export templates when
exporting HTML5 for Godot 3.5. Exports from other Godot versions may
requiring compiling the GDNative library with a different version of the
Emscripten SDK.

- Changes renderer from GLES3 -> GLES2 and reduces MSAA level to better
  support HTML5 export.
- Updates GitHub Action to export HTML5 and upload as a build artifact.
- Adds Cypress test to smoke test HTML5 export.

.github/import_assets.tscn

@@ -0,0 +1,21 @@
+[gd_scene load_steps=2 format=2]
+
+[sub_resource type="GDScript" id=1]
+script/source = "tool
+extends Timer
+
+func _enter_tree():
+	start()
+
+func _on_timeout():
+	get_tree().quit(0)
+"
+
+[node name="Timer" type="Timer"]
+process_mode = 0
+wait_time = 10.0
+one_shot = true
+autostart = true
+script = SubResource( 1 )
+
+[connection signal="timeout" from="." to="." method="_on_timeout"]

.github/workflows/main.yml

@@ -102,7 +102,7 @@ jobs:
         if: ${{ matrix.platform == 'javascript' }}
         uses: mymindstorm/setup-emsdk@v11
         with:
-          version: 3.1.5
+          version: 3.1.14
           actions-cache-folder: emsdk-cache-${{ matrix.target }}
       - name: Install additional javascript build dependencies
         if: ${{ matrix.platform == 'javascript' }}
@@ -168,43 +168,9 @@ jobs:
             addons/godot_xterm/native/bin/*.dylib
             addons/godot_xterm/native/bin/*.dll
 
-  # GDNative HTML5 export templates aren't provided so we must build them
-  export_template:
-    name: 'Export Template'
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        target: [ release, debug ]
-    steps:
-      - uses: actions/checkout@v2
-        with:
-          submodules: recursive
-      - name: Get godot submodule commit hash
-        shell: bash
-        env:
-          ACTIONS_ALLOW_UNSECURE_COMMANDS: true
-        run: |
-          echo ::set-env name=GODOT_COMMIT_HASH::$(git ls-tree HEAD misc/export_templates/godot -l | cut -d\  -f3)
-      - name: Cache export template
-        uses: actions/cache@v2
-        id: cache-export-template
-        env:
-          cache-name: cache-export-template
-        with:
-          path: misc/export_templates/godot/bin
-          key: godot-${{ env.GODOT_COMMIT_HASH }}-${{ matrix.target }}-v${{ env.EXPORT_TEMPLATE_CACHE_VERSION }}
-      - name: Build template in docker container
-        if: steps.cache-export-template.outputs.cache-hit != 'true'
-        run: cd misc/export_templates && ./build.sh -t ${{ matrix.target }}
-      - name: Upload export template
-        uses: actions/upload-artifact@v2
-        with:
-          name: html5-gdnative-export-templates
-          path: misc/export_templates/godot/bin/webassembly_gdnative_${{matrix.target}}.zip
-
   html5_export:
     name: 'HTML5 Export'
-    needs: [ build_docker, build_native, export_template ]
+    needs: [ build_docker, build_native ]
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
@@ -217,23 +183,39 @@ jobs:
       with:
         name: libgodot-xterm-release
         path: addons/godot_xterm/native/bin
-    - name: Install html5 export templates
-      uses: actions/download-artifact@v2
+    - name: Import assets
+      shell: bash
+      # The GodotXterm plugin will be disabled the first time we run the editor as resources that it depends
+      # (e.g. icons) will not have been imported yet so the plugin will fail to load. Without the plugin
+      # enabled resources imported by GodotXterm import plugins (e.g. .cast) will not be imported. Therefore,
+      # we need to re-enable the plugin by checking out project.godot and running the editor again.
+      run: godot --editor .github/import_assets.tscn && git checkout project.godot && godot --editor .github/import_assets.tscn
+    - name: Export HTML5
+      run: godot --no-window --export HTML5
+    - name: NPM cache
+      uses: c-hive/gha-npm-cache@v1
       with:
-        name: html5-gdnative-export-templates
-        path: misc/export_templates/godot/bin
-    - name: Create export directory
-      run: mkdir -p docs/demo
-    - name: Export html5
-      run: godot --export HTML5
-    # FIXME: HTML5 Exports not properly exporting .cast files.
-    # So skip upload for now.
-    #- name: Upload export
-    #  uses: actions/upload-artifact@v2
-    #  with:
-    #    name: html5-demo
-    #    path: docs/demo
-
+        directory: test/html5
+    - name: Smoke test HTML5 export
+      shell: bash
+      working-directory: test/html5
+      run: |
+        npm ci
+        npx serve ../../docs/demo -p 3000 &
+        npx cypress run
+    - name: Upload cypress artifacts (on failure)
+      uses: actions/upload-artifact@v2
+      if: ${{ failure() }}
+      with:
+        name: cypress-artifacts
+        path: |-
+          test/html5/cypress/screenshots
+          test/html5/cypress/videos
+    - name: Upload export
+      uses: actions/upload-artifact@v2
+      with:
+        name: html5-demo
+        path: docs/demo
 
   test:
     name: 'Test'