This PR changes the default TypeScript compilation target fromes5 toesnext to better align with modern JavaScript environments and "evergreen runtimes" that are now the norm.

Changes Made

• Updated the default target fallback insrc/compiler/utilities.ts fromScriptTarget.ES5 toScriptTarget.ESNext
• Updated the help documentation default insrc/compiler/commandLineParser.ts fromScriptTarget.ES5 toScriptTarget.ESNext
• Accepted updated test baselines reflecting the new ESNext output instead of ES5 downleveling

Impact

When no explicit--target is specified, TypeScript will now:

• Preserve modern JavaScript syntax (classes, arrow functions, spread operators, etc.)
• Generate cleaner, more readable output
• Target modern JavaScript environments by default

Before (ES5 default):

// Inputconstx=[1,2,3];console.log(...x);// Output (downleveled)varx=[1,2,3];console.log.apply(console,x);

After (ESNext default):

// Inputconstx=[1,2,3];console.log(...x);// Output (preserved)constx=[1,2,3];console.log(...x);

Migration

This is abreaking change. Users who need ES5 output for compatibility with older environments should explicitly specify--target es5 in theirtsconfig.json:

{"compilerOptions": {"target":"es5"  }}

Tests with explicit// @target: es5 directives continue to work correctly and are unaffected.

Rationale

• ES5 will be deprecated in TypeScript 6.0 and removed in 7.0 (Deprecate--target es5, make lowest targetes2015 #62196)
• Modern JavaScript environments support ESNext features natively
• Reduces unnecessary code transformation and improves output quality
• Aligns with TypeScript's core value proposition as "JavaScript with type syntax"

Fixes#62198.

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