make all tests run in parallel

The subtests were almost all marked as parallel, but that's not enough.
That only makes the subtests run in parallel with other subtests within
the same tests, not with any other test.

Since none of the tests make use of globals nor require the entire
program to themselves, properly run all the tests in parallel.

Speeds up 'go test' on my 8-core laptop from an average of ~130s to an
average of ~50s. Many tests hit timeouts and have sleeps, so we want to
avoid running those sequentially whenever possible.

input_test.go

@@ -21,10 +21,10 @@ const (
 )
 
 func TestMouseClickXY(t *testing.T) {
-	var err error
-
 	t.Parallel()
 
+	var err error
+
 	c := testAllocate(t, "input.html")
 	defer c.Release()
 
@@ -78,6 +78,8 @@ func TestMouseClickXY(t *testing.T) {
 }
 
 func TestMouseClickNode(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel, exp string
 		opt      MouseOption
@@ -128,6 +130,8 @@ func TestMouseClickNode(t *testing.T) {
 }
 
 func TestMouseClickOffscreenNode(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel string
 		exp int
@@ -186,6 +190,8 @@ func TestMouseClickOffscreenNode(t *testing.T) {
 }
 
 func TestKeyAction(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel, exp string
 		by       QueryOption
@@ -238,6 +244,8 @@ func TestKeyAction(t *testing.T) {
 }
 
 func TestKeyActionNode(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel, exp string
 		by       QueryOption

query_test.go

@@ -190,6 +190,8 @@ func TestText(t *testing.T) {
 }
 
 func TestClear(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel string
 		by  QueryOption
@@ -244,6 +246,8 @@ func TestClear(t *testing.T) {
 }
 
 func TestReset(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel   string
 		by    QueryOption
@@ -315,6 +319,8 @@ func TestValue(t *testing.T) {
 }
 
 func TestSetValue(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel string
 		by  QueryOption
@@ -442,6 +448,8 @@ func TestAttributesAll(t *testing.T) {
 }
 
 func TestSetAttributes(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel   string
 		by    QueryOption
@@ -547,6 +555,8 @@ func TestAttributeValue(t *testing.T) {
 }
 
 func TestSetAttributeValue(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel  string
 		by   QueryOption
@@ -589,6 +599,8 @@ func TestSetAttributeValue(t *testing.T) {
 }
 
 func TestRemoveAttribute(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel  string
 		by   QueryOption
@@ -626,6 +638,8 @@ func TestRemoveAttribute(t *testing.T) {
 }
 
 func TestClick(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel string
 		by  QueryOption
@@ -666,6 +680,8 @@ func TestClick(t *testing.T) {
 }
 
 func TestDoubleClick(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel string
 		by  QueryOption
@@ -703,6 +719,8 @@ func TestDoubleClick(t *testing.T) {
 }
 
 func TestSendKeys(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel  string
 		by   QueryOption
@@ -773,6 +791,8 @@ func TestScreenshot(t *testing.T) {
 }
 
 func TestSubmit(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel string
 		by  QueryOption
@@ -813,6 +833,8 @@ func TestSubmit(t *testing.T) {
 }
 
 func TestComputedStyle(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel string
 		by  QueryOption
@@ -870,6 +892,8 @@ func TestComputedStyle(t *testing.T) {
 }
 
 func TestMatchedStyle(t *testing.T) {
+	t.Parallel()
+
 	tests := []struct {
 		sel string
 		by  QueryOption
@@ -952,6 +976,8 @@ func TestFileUpload(t *testing.T) {
 
 	for i, test := range tests {
 		t.Run(fmt.Sprintf("test %d", i), func(t *testing.T) {
+			t.Parallel()
+
 			c := testAllocate(t, "")
 			defer c.Release()