Simplify the app build a little.

Change-Id: I16bf812f5e01a3098d0644298f606970d7e7321a
Reviewed-on: https://code-review.googlesource.com/c/re2/+/61470
Reviewed-by: Paul Wankadia <junyer@google.com>
Reviewed-by: Alex Chernyakhovsky <achernya@google.com>

app/BUILD.bazel

diff --git a/app/BUILD.bazel b/app/BUILD.bazel
index 01ff8d4..50e7e2c 100644
--- a/app/BUILD.bazel
+++ b/app/BUILD.bazel
@@ -10,6 +10,7 @@
     linkopts = [
         "--bind",
         "-sENVIRONMENT=web",
+        "-sSINGLE_FILE=1",
         "-sMODULARIZE=1",
         "-sEXPORT_ES6=1",
         "-sEXPORT_NAME=loadModule",

app/build.sh

diff --git a/app/build.sh b/app/build.sh
index c272bf5..a606d7b 100755
--- a/app/build.sh
+++ b/app/build.sh
@@ -25,13 +25,7 @@
     ${BAZEL} build --compilation_mode=opt \
     --copt=-fno-stack-protector \
     -- :all
-  # Bazel doesn't retain the `_re2.wasm` artifact;
-  # we have to redo the link command to obtain it.
-  pushd ..
-  emcc @bazel-bin/app/_re2.js-2.params
-  cd bazel-bin/app
-  cp _re2.js _re2.wasm ${DSTDIR}
-  popd
+  cp ../bazel-bin/app/_re2.js ${DSTDIR}
   # Clean up the sundry Bazel output directories.
   ${BAZEL} clean --expunge
   cp app.ts index.html _re2.d.ts ${DSTDIR}