Implement DataView builtin (#2804)

New API functions:
 - jerry_create_dataview
 - jerry_value_is_dataview
 - jerry_get_dataview_buffer

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu

docs/02.API-REFERENCE.md

@@ -63,6 +63,7 @@ Possible compile time enabled feature types:
  - JERRY_FEATURE_LINE_INFO - line info available
  - JERRY_FEATURE_LOGGING - logging
  - JERRY_FEATURE_SYMBOL - symbol support
+ - JERRY_FEATURE_DATAVIEW - DataView support
 
 ## jerry_regexp_flags_t
 
@@ -1296,6 +1297,56 @@ jerry_value_is_constructor (const jerry_value_t value)
 
 - [jerry_release_value](#jerry_release_value)
 
+## jerry_value_is_dataview
+
+**Summary**
+
+Returns whether the given `jerry_value_t` is a DataView object value.
+
+**Prototype**
+
+```c
+bool
+jerry_value_is_dataview (const jerry_value_t value)
+```
+
+- `value` - API value
+- return value
+  - true, if the given `jerry_value_t` is a DataView object
+  - false, otherwise
+
+**Example**
+
+[doctest]: # ()
+
+```c
+#include "jerryscript.h"
+
+int
+main (void)
+{
+  jerry_init (JERRY_INIT_EMPTY);
+
+  jerry_value_t arraybuffer = jerry_create_arraybuffer (16);
+  jerry_value_t dataview = jerry_create_dataview (arraybuffer, 0, 16);
+
+  if (jerry_value_is_dataview (dataview))
+  {
+    // usage of dataview
+  }
+
+  jerry_release_value (dataview);
+  jerry_release_value (arraybuffer);
+
+  jerry_cleanup ();
+}
+```
+
+**See also**
+
+- [jerry_release_value](#jerry_release_value)
+
+
 ## jerry_value_is_error
 
 **Summary**
@@ -3246,6 +3297,62 @@ jerry_create_error_sz (jerry_error_t error_type,
 - [jerry_create_error](#jerry_create_error)
 
 
+## jerry_create_dataview
+
+**Summary**
+
+Create new JavaScript DataView object.
+
+*Note*: This API depends on the ES2015-subset profile.
+*Note*: Returned value must be freed with [jerry_release_value](#jerry_release_value) when it
+is no longer needed.
+
+**Prototype**
+
+```c
+jerry_value_t
+jerry_create_dataview (const jerry_value_t array_buffer,
+                       const jerry_length_t byte_offset,
+                       const jerry_length_t byte_length)
+```
+
+- `array_buffer` - arrayBuffer to create DataView from
+- `byte_offset` - offset in bytes, to the first byte in the buffer
+- `byte_length` - number of elements in the byte array
+- return value
+  - value of the constructed DataView object - if success
+  - created error - otherwise
+
+**Example**
+
+[doctest]: # ()
+
+```c
+#include "jerryscript.h"
+
+int
+main (void)
+{
+  jerry_init (JERRY_INIT_EMPTY);
+
+  jerry_value_t arraybuffer = jerry_create_arraybuffer (16);
+  jerry_value_t dataview = jerry_create_dataview (arraybuffer, 0, 16);
+
+  // usage of dataview
+
+  jerry_release_value (dataview);
+  jerry_release_value (arraybuffer);
+
+  jerry_cleanup ();
+}
+```
+
+**See also**
+
+- [jerry_value_is_dataview](#jerry_value_is_dataview)
+- [jerry_create_arraybuffer](#jerry_create_arraybuffer)
+
+
 ## jerry_create_external_function
 
 **Summary**
@@ -6254,6 +6361,70 @@ jerry_get_arraybuffer_pointer (const jerry_value_t value);
 - [jerry_create_arraybuffer_external](#jerry_create_arraybuffer_external)
 
 
+## jerry_get_dataview_buffer
+
+**Summary**
+
+Get the ArrayBuffer object used by a DataView object.
+Additionally returns the byteLength and byteOffset properties
+of the DataView object.
+
+For the returned ArrayBuffer the [jerry_release_value](#jerry_release_value)
+must be called when it is no longer needed.
+
+**Prototype**
+
+```c
+jerry_value_t
+jerry_get_dataview_buffer (const jerry_value_t value,
+                           jerry_length_t *byteOffset,
+                           jerry_length_t *byteLength);
+```
+
+- `value` - DataView to get the ArrayBuffer from
+- `byteOffset` - (Optional) returns the start offset of the ArrayBuffer for the DataView
+- `byteLength` - (Optional) returns the number of bytes used from the ArrayBuffer for the DataView
+- return
+  - DataView object's underlying ArrayBuffer object
+  - TypeError if the `value` is not a DataView object
+
+**Example**
+
+[doctest]: # ()
+
+```c
+#include "jerryscript.h"
+
+int
+main (void)
+{
+  jerry_init (JERRY_INIT_EMPTY);
+
+  jerry_value_t arraybuffer = jerry_create_arraybuffer (16);
+  jerry_value_t dataview = jerry_create_dataview (arraybuffer, 0, 16);
+  jerry_length_t byteOffset = 0;
+  jerry_length_t byteLength = 0;
+  jerry_value_t buffer = jerry_get_dataview_buffer (dataview, &byteOffset, &byteLength);
+
+  // buffer is an ArrayBuffer object and ArrayBuffer operations can be performed on it
+  // byteOffset is 0
+  // byteLength is 16
+
+  // usage of buffer
+
+  jerry_release_value (buffer);
+  jerry_release_value (dataview);
+  jerry_release_value (arraybuffer);
+
+  jerry_cleanup ();
+}
+```
+
+**See also**
+
+- [jerry_create_dataview](#jerry_create_dataview)
+
+
 ## jerry_get_typedarray_type
 
 **Summary**