impr: Try to detect backing scaling factor on the web build

lib/libimhex/source/api/imhex_api.cpp

@@ -638,12 +638,13 @@ namespace hex {
                     return std::midpoint(xScale, yScale);
                 }
             #elif defined(OS_WEB)
-                return 1.0F;
+                return MAIN_THREAD_EM_ASM_INT({
-                /*
+                    try {
-                return EM_ASM_INT({
                         return window.devicePixelRatio;
+                    } catch (e) {
+                        return 1.0;
+                    }
                 });
-                */
             #else
                 return 1.0F;
             #endif