use String.prototype.endsWith instead of .lastIndexOf with a length comparison

Author: toshok

lib/compiler.js

@@ -2577,7 +2577,7 @@ function insert_toplevel_func (tree, moduleInfo) {
 export function compile (tree, base_output_filename, source_filename, module_infos, options) {
     let abi = (options.target_arch === "armv7" || options.target_arch === "armv7s" || options.target_arch === "x86") ? new SRetABI() : new ABI();
 
-    if (source_filename.lastIndexOf(".js") == source_filename.length - 3)
+    if (source_filename.endsWith(".js"))
         source_filename = source_filename.substring(0, source_filename.length-3);
 
     let this_module_info = module_infos.get(source_filename);

lib/passes/gather-imports.js

@@ -54,7 +54,7 @@ class GatherImports extends TreeVisitor {
 
         this.importList = [];
         // remove our .js suffix since all imports are suffix-free
-        if (this.filename.lastIndexOf(".js") === this.filename.length - 3)
+        if (this.filename.endsWith(".js"))
             this.filename = this.filename.substring(0, this.filename.length-3);
 
         this.moduleInfo = new JSModuleInfo(this.filename);