Auto merge of #19498 - ferjm:pwm.f64, r=jdm

Fix float conversion of paint timing metrics

This is a follow up of #19077

- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors

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components/script/dom/performance.rs

@@ -20,6 +20,7 @@ use dom::performanceobserver::PerformanceObserver as DOMPerformanceObserver;
 use dom::performancetiming::PerformanceTiming;
 use dom::window::Window;
 use dom_struct::dom_struct;
+use metrics::ToMs;
 use std::cell::Cell;
 use std::cmp::Ordering;
 use time;
@@ -260,7 +261,7 @@ impl Performance {
             Some(ref timing) => timing.navigation_start_precise(),
             None => self.navigation_start_precise,
         };
-        (time::precise_time_ns() - nav_start) as f64 / 1000000.
+        (time::precise_time_ns() - nav_start).to_ms()
     }
 }
 

components/script/dom/performancepainttiming.rs

@@ -9,6 +9,7 @@ use dom::bindings::str::DOMString;
 use dom::globalscope::GlobalScope;
 use dom::performanceentry::PerformanceEntry;
 use dom_struct::dom_struct;
+use metrics::ToMs;
 use script_traits::ProgressiveWebMetricType;
 
 #[dom_struct]
@@ -26,7 +27,7 @@ impl PerformancePaintTiming {
         PerformancePaintTiming {
             entry: PerformanceEntry::new_inherited(name,
                                                    DOMString::from("paint"),
-                                                   start_time as f64,
+                                                   start_time.to_ms(),
                                                    0.)
         }
     }