WebGLProgram: Add GLSL version string to RawShaderMateiral (WebGL2).

src/renderers/webgl/WebGLProgram.js

@@ -433,6 +433,15 @@ function WebGLProgram( renderer, cacheKey, parameters, bindingStates ) {
 
 		}
 
+		if ( parameters.isWebGL2 === true ) {
+
+			const glslVersionString = '#version 300 es\n';
+
+			prefixVertex = glslVersionString + prefixVertex;
+			prefixFragment = glslVersionString + prefixFragment;
+
+		}
+
 	} else {
 
 		prefixVertex = [