add dev env for wasm

with this I get 5s compilations

Author: andrewrk

src/dev.zig

@@ -30,6 +30,10 @@ pub const Env = enum {
     /// - `zig build-* -fno-llvm -fno-lld -target riscv64-linux`
     @"riscv64-linux",
 
+    /// - sema
+    /// - `zig build-* -fno-llvm -fno-lld -target wasm32-* --listen=-`
+    wasm,
+
     pub inline fn supports(comptime dev_env: Env, comptime feature: Feature) bool {
         return switch (dev_env) {
             .full => true,
@@ -144,6 +148,14 @@ pub const Env = enum {
                 => true,
                 else => Env.sema.supports(feature),
             },
+            .wasm => switch (feature) {
+                .stdio_listen,
+                .incremental,
+                .wasm_backend,
+                .wasm_linker,
+                => true,
+                else => Env.sema.supports(feature),
+            },
         };
     }