revert: remove platform-specific browser helper variant logic from binder.ts (reverts 34c79d6)

Co-authored-by: v-jiaodi <80496810+v-jiaodi@users.noreply.github.com>

Author: Copilot

packages/typespec-test/test/batch_modular/generated/typespec-ts/src/static-helpers/serialization/get-binary-response-browser.mts

@@ -309,39 +309,6 @@ class BinderImp implements Binder {
       }
     }
 
-    // Ensure platform-specific variants (e.g. *-browser.*, *-react-native.*)
-    // are preserved whenever their base helper is referenced.
-    const platformSuffixes = ["-browser", "-react-native"];
-    const helpersWithReferences = Array.from(usedHelperFiles);
-    for (const helperFile of helpersWithReferences) {
-      const directory = helperFile.getDirectory();
-      const filePath = helperFile.getFilePath();
-      const fileName = path.basename(filePath);
-      const dotIndex = fileName.indexOf(".");
-      const baseName =
-        dotIndex === -1 ? fileName : fileName.substring(0, dotIndex);
-      const variantPrefix = `${baseName}-`;
-
-      for (const sibling of directory.getSourceFiles()) {
-        if (usedHelperFiles.has(sibling)) {
-          continue;
-        }
-        const siblingPath = sibling.getFilePath();
-        const siblingName = path.basename(siblingPath);
-        const siblingDotIndex = siblingName.indexOf(".");
-        const siblingBaseName =
-          siblingDotIndex === -1
-            ? siblingName
-            : siblingName.substring(0, siblingDotIndex);
-
-        if (
-          siblingBaseName.startsWith(variantPrefix) &&
-          platformSuffixes.some((suffix) => siblingBaseName.endsWith(suffix))
-        ) {
-          usedHelperFiles.add(sibling);
-        }
-      }
-    }
     function isFileUnused(file: SourceFile) {
       return !usedHelperFiles.has(file);
     }