WebGLRenderer: Support for BufferGeometry with material.wireframe = true.

Not pretty but better than nothing I guess.

src/renderers/WebGLRenderer.js

@@ -2500,6 +2500,8 @@ THREE.WebGLRenderer = function ( parameters ) {
 
 		if ( object instanceof THREE.Mesh ) {
 
+			var mode = material.wireframe === true ? _gl.LINES : _gl.TRIANGLES;
+
 			var index = geometry.attributes.index;
 
 			if ( index ) {
@@ -2531,7 +2533,7 @@ THREE.WebGLRenderer = function ( parameters ) {
 
 					}
 
-					_gl.drawElements( _gl.TRIANGLES, index.array.length, type, 0 );
+					_gl.drawElements( mode, index.array.length, type, 0 );
 
 					_this.info.render.calls ++;
 					_this.info.render.vertices += index.array.length; // not really true, here vertices can be shared
@@ -2558,7 +2560,7 @@ THREE.WebGLRenderer = function ( parameters ) {
 
 						// render indexed triangles
 
-						_gl.drawElements( _gl.TRIANGLES, offsets[ i ].count, type, offsets[ i ].start * size );
+						_gl.drawElements( mode, offsets[ i ].count, type, offsets[ i ].start * size );
 
 						_this.info.render.calls ++;
 						_this.info.render.vertices += offsets[ i ].count; // not really true, here vertices can be shared
@@ -2582,7 +2584,7 @@ THREE.WebGLRenderer = function ( parameters ) {
 
 				// render non-indexed triangles
 
-				_gl.drawArrays( _gl.TRIANGLES, 0, position.array.length / 3 );
+				_gl.drawArrays( mode, 0, position.array.length / 3 );
 
 				_this.info.render.calls ++;
 				_this.info.render.vertices += position.array.length / 3;