Feature/#250 wait style (#255)

* Added support for parsed styles

* Added stdlib function.

* Added e2e tests

* Added e2e tests for STYLE_* functions

pkg/stdlib/html/style_get.go

@@ -0,0 +1,44 @@
+package html
+
+import (
+	"context"
+
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/MontFerret/ferret/pkg/runtime/values"
+)
+
+// StyleGet gets single or more style attribute value(s) of a given element.
+// @param el (HTMLElement) - Target element.
+// @param names (...String) - Style name(s).
+// @returns Object - Key-value pairs of style values.
+func StyleGet(ctx context.Context, args ...core.Value) (core.Value, error) {
+	err := core.ValidateArgs(args, 2, core.MaxArgs)
+
+	if err != nil {
+		return values.None, err
+	}
+
+	el, err := resolveElement(args[0])
+
+	if err != nil {
+		return values.None, err
+	}
+
+	names := args[1:]
+	result := values.NewObject()
+
+	for _, n := range names {
+		name := values.NewString(n.String())
+		val, err := el.GetStyle(ctx, name)
+
+		if err != nil {
+			return values.None, err
+		}
+
+		if val != values.None {
+			result.Set(name, val)
+		}
+	}
+
+	return result, nil
+}