Reset the class of each captured call

ext/fiber/profiler/capture.c

@@ -140,6 +140,7 @@ void Fiber_Profiler_Capture_Call_initialize(void *element) {
 
 	call->event_flag = 0;
 	call->id = 0;
+	call->klass = Qnil;
 
 	call->path = NULL;
 	call->line = 0;

test/fiber/profiler/capture.rb

@@ -185,6 +185,28 @@ def nested(n = 100, &block)
 		end
 	end
 
+	with "blocks outside of methods" do
+		# Blocks defined outside of a method don't have a method or class:
+		work = proc do
+			String.new
+			[1, 2].each{sleep 0.001}
+		end
+
+		it "doesn't report a class left over from an earlier call" do
+			capture.start
+
+			Fiber.new(&work).resume
+
+			capture.stop
+
+			stall = JSON.parse(output.string)
+			classes = stall["calls"].map{|call| call["class"]}
+
+			expect(classes).not.to have_value(be == "String")
+			expect(classes).not.to have_value(be == "false")
+		end
+	end
+
 	with "Process.fork" do
 		it "should disable the profiler in the child process after fork" do
 			capture.start