I have the same problem on mac, the game goes unresponsive just as i try to use the flash and when i refresh i get this error message
ERROR: CanvasShaderGLES3: Vertex shader compilation failed:
ERROR: 0:4: '' : syntax error: #extension must always be before any non-preprocessor tokens
WARNING: 0:4: extension 'GL_ARB_shading_language_packing' is not supported
at: _display_error_with_code (drivers/gles3/shader_gles3.cpp:259)
>>v0.9.1 -- Default -- <null> -- Web - false<<ERROR: Method/function failed.
at: _compile_specialization (drivers/gles3/shader_gles3.cpp:353)
>>v0.9.1 -- Default -- <null> -- Web - false<<