Simplify WebGL example

[ibaryshnikov]

Motivation

There is a function signature

pub fn link_program<'a, T: IntoIterator<Item = &'a WebGlShader>>(
    context: &WebGlRenderingContext,
    shaders: T,
) -> Result<WebGlProgram, String> {

It's hard to teach, because it requires additional explanations about iterators and lifetimes.
There is also String::from("") and "".into(), which produces the question "why are they different?".

Proposed Solution

Use distinct arguments instead of the iterator

pub fn link_program(
    context: &WebGlRenderingContext,
    vert_shader: &WebGlShader,
    frag_shader: &WebGlShader,
) -> Result<WebGlProgram, String> {

Alternatives

Keep it as is

Additional Context

I'd like to submit an update for this example if it's a good idea

[alexcrichton]

Sounds great to me! If you'd like to send a PR I'm sure we can find someone happy to review :)

[ibaryshnikov]

Should I also update it to a new behavior (like in without-a-bundler example)? At the moment npm run serve builds the page, but the code fails to run when I navigate to the browser.

[alexcrichton]

Hm these are unfortunately likely broken on master due to #1318, which I hope to fix today