Refined "Drop support for ruby 2.4 from ruby/spec"

By using spec/mspec/tool/remove_old_guards.rb.

spec/ruby/core/file/utime_spec.rb

@@ -3,7 +3,7 @@ require_relative '../../spec_helper'
 describe "File.utime" do
 
   before :all do
-    @time_is_float = /mswin|mingw/ =~ RUBY_PLATFORM && RUBY_VERSION >= '2.5'
+    @time_is_float = /mswin|mingw/ =~ RUBY_PLATFORM
   end
 
   before :each do

spec/ruby/core/integer/shared/arithmetic_coerce.rb

@@ -1,5 +1,25 @@
 require_relative '../fixtures/classes'
 
+describe :integer_arithmetic_coerce_rescue, shared: true do
+  it "rescues exception (StandardError and subclasses) raised in other#coerce and raises TypeError" do
+    b = mock("numeric with failed #coerce")
+    b.should_receive(:coerce).and_raise(IntegerSpecs::CoerceError)
+
+    # e.g. 1 + b
+    -> { 1.send(@method, b) }.should raise_error(TypeError, /MockObject can't be coerced into Integer/)
+  end
+
+  it "does not rescue Exception and StandardError siblings raised in other#coerce" do
+    [Exception, NoMemoryError].each do |exception|
+      b = mock("numeric with failed #coerce")
+      b.should_receive(:coerce).and_raise(exception)
+
+      # e.g. 1 + b
+      -> { 1.send(@method, b) }.should raise_error(exception)
+    end
+  end
+end
+
 describe :integer_arithmetic_coerce_not_rescue, shared: true do
   it "does not rescue exception raised in other#coerce" do
     b = mock("numeric with failed #coerce")

spec/ruby/language/return_spec.rb

@@ -361,6 +361,22 @@ describe "The return keyword" do
         END_OF_CODE
       end
 
+      it "fires ensure block before returning while loads file" do
+        File.write(@filename, <<-END_OF_CODE)
+          ScratchPad << "before begin"
+          begin
+            return
+          ensure
+            ScratchPad << "within ensure"
+          end
+
+          ScratchPad << "after begin"
+        END_OF_CODE
+
+        load @filename
+        ScratchPad.recorded.should == ["before begin", "within ensure"]
+      end
+
       it "swallows exception if returns in ensure block" do
         File.write(@filename, <<-END_OF_CODE)
           begin

spec/ruby/library/conditionvariable/wait_spec.rb

@@ -106,7 +106,6 @@ describe "ConditionVariable#wait" do
     owned.should == true
   end
 
-  ruby_bug '#14999', ''...'2.5' do
   it "reacquires the lock even if the thread is killed after being signaled" do
     m = Mutex.new
     cv = ConditionVariable.new
@@ -141,7 +140,6 @@ describe "ConditionVariable#wait" do
     th.join
     owned.should == true
   end
-  end
 
   it "supports multiple Threads waiting on the same ConditionVariable and Mutex" do
     m = Mutex.new