Bug 1684689 - Fix usage of createImageData in devtools. r=jdescottes

This fixes the DAMP failures and effectively preserves behavior.

Differential Revision: https://phabricator.services.mozilla.com/D100623

devtools/client/netmonitor/src/widgets/WaterfallBackground.js

@@ -59,8 +59,10 @@ class WaterfallBackground {
     }
 
     // Nuke the context.
-    const canvasWidth = (this.canvas.width =
-      state.waterfallWidth - REQUESTS_WATERFALL.LABEL_WIDTH);
+    const canvasWidth = (this.canvas.width = Math.max(
+      state.waterfallWidth - REQUESTS_WATERFALL.LABEL_WIDTH,
+      1
+    ));
     // Awww yeah, 1px, repeats on Y axis.
     const canvasHeight = (this.canvas.height = 1);
 

devtools/client/performance/modules/waterfall-ticks.js

@@ -22,7 +22,7 @@ function drawWaterfallBackground(doc, dataScale, waterfallWidth) {
   const ctx = canvas.getContext("2d");
 
   // Nuke the context.
-  const canvasWidth = (canvas.width = waterfallWidth);
+  const canvasWidth = (canvas.width = Math.max(waterfallWidth, 1));
   // Awww yeah, 1px, repeats on Y axis.
   const canvasHeight = (canvas.height = 1);