Bug 1828008 - Avoid creating timers with a delay of UINT32_MAX in nsCaret::ResetBlinking, r=emilio.

Differential Revision: https://phabricator.services.mozilla.com/D175421

layout/base/nsCaret.cpp

@@ -604,7 +604,7 @@ void nsCaret::ResetBlinking() {
   }
 
   auto blinkRate =
-      uint32_t(LookAndFeel::GetInt(IntID::CaretBlinkTime, kDefaultBlinkRate));
+      LookAndFeel::GetInt(IntID::CaretBlinkTime, kDefaultBlinkRate);
 
   if (blinkRate > 0) {
     // Make sure to reset the remaining blink count even if the blink rate

layout/base/nsCaret.h

@@ -252,9 +252,9 @@ class nsCaret final : public nsISelectionListener {
   /**
    * mBlinkRate is the rate of the caret blinking the last time we read it.
    * It is used as a way to optimize whether we need to reset the blinking
-   * timer.
+   * timer. 0 or a negative value means no blinking.
    */
-  uint32_t mBlinkRate;
+  int32_t mBlinkRate;
   /**
    * mHideCount is not 0, it means that somebody doesn't want the caret
    * to be visible.  See AddForceHide() and RemoveForceHide().