Switch the --browser argument to --web

This commit reverts part of the implementation of [RFC 6]. That RFC
specified that the `--browser` flag was going to be repurposed for the
new "natively loadable as ES module output", but unfortunately the
breakage is far broader than initially expected. It turns out that
`wasm-pack` passes `--browser` by default which means that a change to
break `--browser` would break all historical versions of `wasm-pack`
which is a bit much for now.

To solve this the `--browser` flag is going back to what it represents
on the current released version of `wasm-bindgen` (optimize away some
node.js checks in a few places for bundler-style output) and a new
`--web` flag is being introduced as the new deployment strategy.

[RFC 6]: https://github.com/rustwasm/rfcs/pull/6

Closes #1318

examples/without-a-bundler-no-modules/README.md

@@ -14,8 +14,8 @@ and then opening `index.html` in a browser should run the example!
 
 Note that this example is in contrast to the [without a bundler][wab] example
 which performs a similar purpose except it uses `--no-modules` instead of
-`--browser`. The main difference here is how the shim JS and module are loaded,
-where this example uses old-school `script` tags while `--browser` uses ES
+`--web`. The main difference here is how the shim JS and module are loaded,
+where this example uses old-school `script` tags while `--web` uses ES
 modules.
 
 [wab]: https://github.com/rustwasm/wasm-bindgen/tree/master/examples/without-a-bundler

examples/without-a-bundler-no-modules/index.html

@@ -7,8 +7,8 @@
     <script src='pkg/without_a_bundler_no_modules.js'></script>
 
     <script type=module>
-      // Like with the `--browser` output the exports are immediately available
-      // but they won't work until we initialize the module. Unlike `--browser`,
+      // Like with the `--web` output the exports are immediately available
+      // but they won't work until we initialize the module. Unlike `--web`,
       // however, the globals are all stored on a `wasm_bindgen` global. The
       // global itself is the initialization function and then the properties of
       // the global are all the exported functions.

examples/without-a-bundler/README.md

@@ -11,7 +11,7 @@ $ cargo build --target wasm32-unknown-unknown --release
 $ cargo run -p wasm-bindgen-cli --bin wasm-bindgen -- \
   ../../target/wasm32-unknown-unknown/release/without_a_bundler.wasm \
   --out-dir pkg \
-  --browser
+  --web
 ```
 
 and then opening `index.html` in a browser should run the example!

examples/without-a-bundler/build.sh

@@ -3,13 +3,13 @@
 set -ex
 
 # Note that typically we'd use `wasm-pack` to build the crate, but the
-# `--browser` flag is very new to `wasm-bindgen` and as such doesn't have
+# `--web` flag is very new to `wasm-bindgen` and as such doesn't have
 # support in `wasm-pack` yet. Support will be added soon though!
 
 cargo build --target wasm32-unknown-unknown --release
 cargo run --manifest-path ../../crates/cli/Cargo.toml \
     --bin wasm-bindgen -- \
     ../../target/wasm32-unknown-unknown/release/without_a_bundler.wasm --out-dir pkg \
-    --browser
+    --web
 
 python3 -m http.server