Add tiny-triangle.gltf fixture asset

fixtures/assets/tiny-triangle.gltf

@@ -0,0 +1,64 @@
+{
+  "asset": {
+    "version": "2.0",
+    "generator": "webeditor3d fixture"
+  },
+  "scene": 0,
+  "scenes": [
+    {
+      "nodes": [0]
+    }
+  ],
+  "nodes": [
+    {
+      "mesh": 0,
+      "name": "Fixture Triangle Node"
+    }
+  ],
+  "meshes": [
+    {
+      "name": "Fixture Triangle Mesh",
+      "primitives": [
+        {
+          "attributes": {
+            "POSITION": 0
+          },
+          "material": 0
+        }
+      ]
+    }
+  ],
+  "materials": [
+    {
+      "name": "Fixture Material",
+      "pbrMetallicRoughness": {
+        "baseColorFactor": [0.8, 0.5, 0.2, 1],
+        "metallicFactor": 0,
+        "roughnessFactor": 1
+      }
+    }
+  ],
+  "buffers": [
+    {
+      "byteLength": 36,
+      "uri": "data:application/octet-stream;base64,AAAAAAAAAAAAAAAAAACAPwAAAAAAAAAAAAAAAAAAgD8AAAAA"
+    }
+  ],
+  "bufferViews": [
+    {
+      "buffer": 0,
+      "byteOffset": 0,
+      "byteLength": 36
+    }
+  ],
+  "accessors": [
+    {
+      "bufferView": 0,
+      "componentType": 5126,
+      "count": 3,
+      "type": "VEC3",
+      "min": [0, 0, 0],
+      "max": [1, 1, 0]
+    }
+  ]
+}