[wasm] Minor cleanup in wasm module builder

This addresses a review comment from
https://github.com/WebAssembly/spec/pull/1214.

R=ahaas@chromium.org

Change-Id: Icd473aa16bbf35839556b052271489a2889fe0fb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2257229Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68461}

test/mjsunit/wasm/wasm-module-builder.js

@@ -1119,14 +1119,10 @@ class WasmModuleBuilder {
               section.emit_u64v(global.init);
               break;
             case kWasmF32:
-              section.emit_u8(kExprF32Const);
-              data_view.setFloat32(0, global.init, true);
-              section.emit_bytes(byte_view.subarray(0, 4));
+              section.emit_bytes(wasmF32Const(global.init));
               break;
             case kWasmF64:
-              section.emit_u8(kExprF64Const);
-              data_view.setFloat64(0, global.init, true);
-              section.emit_bytes(byte_view);
+              section.emit_bytes(wasmF64Const(global.init));
               break;
             case kWasmExternRef:
               section.emit_u8(kExprRefNull);