[wasm] Enable SWIFT_ENABLE_EXPERIMENTAL_REFLECTION for stdlib to fix test failures

Author: kateinoigakukun

utils/webassembly/build-toolchain.sh

@@ -149,6 +149,7 @@ build_target_toolchain() {
     -D SWIFT_ENABLE_EXPERIMENTAL_DIFFERENTIABLE_PROGRAMMING=YES \
     -D SWIFT_ENABLE_EXPERIMENTAL_DISTRIBUTED=YES \
     -D SWIFT_ENABLE_EXPERIMENTAL_STRING_PROCESSING=YES \
+    -D SWIFT_ENABLE_EXPERIMENTAL_REFLECTION=YES \
     -D SWIFT_PATH_TO_SWIFT_SYNTAX_SOURCE="$SOURCE_PATH/swift-syntax" \
     -D SWIFT_PATH_TO_STRING_PROCESSING_SOURCE="$SOURCE_PATH/swift-experimental-string-processing" \
     -G Ninja \