timers: float delays can cause 100% cpu usage.

lib/timers.js

@@ -53,6 +53,9 @@ function insert(item, msecs) {
   item._idleStart = Date.now();
   item._monotonicStartTime = Timer.now();
 
+  // fractional delay values are not allowed; (0, 1) range
+  // should be coerced to 1ms.
+  msecs = Math.ceil(msecs);
   item._idleTimeout = msecs;
 
   if (msecs < 0) return;

test/simple/test-timers-fractional-settimeout.js

@@ -0,0 +1,21 @@
+var times = 0;
+
+setInterval(function() {
+  process.stderr.write('.')
+}, 0);
+
+setTimeout(function() {
+  process.exit(times === 3 ? 0 : 1);
+}, 102);
+
+var a = setTimeout(function() {
+  ++times;
+}, 100.3);
+
+var b = setTimeout(function() {
+  ++times;
+}, 4.3);
+
+var c = setTimeout(function() {
+  ++times;
+}, 100);