Remove usage of performance.now in TextModelWithTokens (#1439)

src/vs/base/common/stopwatch.ts

@@ -10,27 +10,32 @@ var hasPerformanceNow = (globals.performance && typeof globals.performance.now =
 
 export class StopWatch {
 
+	private _highResolution: boolean;
 	private _startTime: number;
 	private _stopTime: number;
 
-	public static create(): StopWatch {
-		return new StopWatch(hasPerformanceNow ? globals.performance.now() : new Date().getTime());
+	public static create(highResolution:boolean = true): StopWatch {
+		return new StopWatch(highResolution);
 	}
 
-	constructor(startTime: number) {
-		this._startTime = startTime;
+	constructor(highResolution: boolean) {
+		this._highResolution = hasPerformanceNow && highResolution;
+		this._startTime = this._now();
 		this._stopTime = -1;
 	}
 
 	public stop(): void {
-		this._stopTime = (hasPerformanceNow ? globals.performance.now() : new Date().getTime());
+		this._stopTime = this._now();
 	}
 
 	public elapsed(): number {
 		if (this._stopTime !== -1) {
 			return this._stopTime - this._startTime;
 		}
-		var now = (hasPerformanceNow ? globals.performance.now() : new Date().getTime());
-		return now - this._startTime;
+		return this._now() - this._startTime;
+	}
+
+	private _now(): number {
+		return this._highResolution ? globals.performance.now() : new Date().getTime();
 	}
 }

src/vs/editor/common/model/textModelWithTokens.ts

@@ -600,7 +600,7 @@ export class TextModelWithTokens extends TextModel implements editorCommon.IToke
 			currentCharsToTokenize = 0,
 			currentEstimatedTimeToTokenize = 0,
 			stopLineTokenizationAfter = this._stopLineTokenizationAfter,
-			sw = StopWatch.create(),
+			sw = StopWatch.create(false),
 			elapsedTime: number;
 
 		// Tokenize at most 1000 lines. Estimate the tokenization speed per character and stop when:
@@ -682,7 +682,7 @@ export class TextModelWithTokens extends TextModel implements editorCommon.IToke
 			stopLineTokenizationAfter = 1000000000; // 1 billion, if a line is so long, you have other trouble :).
 		}
 
-		var sw = StopWatch.create();
+		var sw = StopWatch.create(false);
 		var tokenizedCharacters = 0;
 
 		var fromLineNumber = this._invalidLineStartIndex + 1, toLineNumber = lineNumber;