Use strict equality in extension check.

src/renderers/webgl/WebGLLights.js

@@ -418,12 +418,12 @@ function WebGLLights( extensions, capabilities ) {
 
 				// WebGL 1
 
-				if ( extensions.has( 'OES_texture_float_linear' ) == true ) {
+				if ( extensions.has( 'OES_texture_float_linear' ) === true ) {
 
 					state.rectAreaLTC1 = UniformsLib.LTC_FLOAT_1;
 					state.rectAreaLTC2 = UniformsLib.LTC_FLOAT_2;
 
-				} else if ( extensions.has( 'OES_texture_half_float_linear' ) == true ) {
+				} else if ( extensions.has( 'OES_texture_half_float_linear' ) === true ) {
 
 					state.rectAreaLTC1 = UniformsLib.LTC_HALF_1;
 					state.rectAreaLTC2 = UniformsLib.LTC_HALF_2;