build/lib/mangleTypeScript.ts/StaticLanguageServiceHost/getScriptSnapshot
class StaticLanguageServiceHost:	getScriptSnapshot(fileName: string): ts.IScriptSnapshot | undefined {
		let result: ts.IScriptSnapshot | undefined = this._scriptSnapshots.get(fileName);
		if (result === undefined) {
			const content = ts.sys.readFile(fileName);
			if (content === undefined) {
				return undefined;
			}
			result = ts.ScriptSnapshot.fromString(content);
			this._scriptSnapshots.set(fileName, result);
		}
		return result;
	}