Enable h2 to be able to run in browser environment.

This replaces Instant by a more generate wasm_timer::Instant.

Cargo.toml

@@ -52,6 +52,7 @@ tracing-futures = { version = "0.2", default-features = false, features = ["std-
 fnv = "1.0.5"
 slab = "0.4.2"
 indexmap = "1.0"
+wasm-timer = { version = "0.2.5" }
 
 [dev-dependencies]
 

src/proto/streams/recv.rs

@@ -5,10 +5,11 @@ use crate::{frame, proto};
 use std::task::Context;
 
 use http::{HeaderMap, Request, Response};
+use wasm_timer::Instant;
 
 use std::io;
 use std::task::{Poll, Waker};
-use std::time::{Duration, Instant};
+use std::time::Duration;
 
 #[derive(Debug)]
 pub(super) struct Recv {

src/proto/streams/stream.rs

@@ -1,7 +1,8 @@
 use super::*;
 
+use wasm_timer::Instant;
+
 use std::task::{Context, Waker};
-use std::time::Instant;
 use std::usize;
 
 /// Tracks Stream related state