diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index bd2f8191720..7e48ba60d34 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -180,13 +180,21 @@ impl WebGLRenderingContext {
             .unwrap();
     }
 
+    fn validate_stencil_actions(&self, action: u32) -> bool {
+        match action {
+            0 | constants::KEEP | constants::REPLACE | constants::INCR | constants::DECR |
+            constants::INVERT | constants::INCR_WRAP | constants::DECR_WRAP => true,
+            _ => false,
+        }
+    }
+
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.10
     // https://www.khronos.org/opengles/sdk/docs/man/xhtml/glUniform.xml
     // https://www.khronos.org/registry/gles/specs/2.0/es_full_spec_2.0.25.pdf#nameddest=section-2.10.4
     fn validate_uniform_parameters<T>(&self,
-                                   uniform: Option<&WebGLUniformLocation>,
-                                   uniform_type: UniformSetterType,
-                                   data: Option<&[T]>) -> bool {
+                                      uniform: Option<&WebGLUniformLocation>,
+                                      uniform_type: UniformSetterType,
+                                      data: Option<&[T]>) -> bool {
         let uniform = match uniform {
             Some(uniform) => uniform,
             None => return false,
@@ -1219,6 +1227,82 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
             .unwrap()
     }
 
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.3
+    fn StencilFunc(&self, func: u32, ref_: i32, mask: u32) {
+        match func {
+            constants::NEVER | constants::LESS | constants::EQUAL | constants::LEQUAL |
+            constants::GREATER | constants::NOTEQUAL | constants::GEQUAL | constants::ALWAYS =>
+                self.ipc_renderer
+                    .send(CanvasMsg::WebGL(WebGLCommand::StencilFunc(func, ref_, mask)))
+                    .unwrap(),
+            _ => self.webgl_error(InvalidEnum),
+        }
+    }
+
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.3
+    fn StencilFuncSeparate(&self, face: u32, func: u32, ref_: i32, mask: u32) {
+        match face {
+            constants::FRONT | constants::BACK | constants::FRONT_AND_BACK => (),
+            _ => return self.webgl_error(InvalidEnum),
+        }
+
+        match func {
+            constants::NEVER | constants::LESS | constants::EQUAL | constants::LEQUAL |
+            constants::GREATER | constants::NOTEQUAL | constants::GEQUAL | constants::ALWAYS =>
+                self.ipc_renderer
+                    .send(CanvasMsg::WebGL(WebGLCommand::StencilFuncSeparate(face, func, ref_, mask)))
+                    .unwrap(),
+            _ => self.webgl_error(InvalidEnum),
+        }
+    }
+
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.3
+    fn StencilMask(&self, mask: u32) {
+        self.ipc_renderer
+            .send(CanvasMsg::WebGL(WebGLCommand::StencilMask(mask)))
+            .unwrap()
+    }
+
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.3
+    fn StencilMaskSeparate(&self, face: u32, mask: u32) {
+        match face {
+            constants::FRONT | constants::BACK | constants::FRONT_AND_BACK =>
+                self.ipc_renderer
+                    .send(CanvasMsg::WebGL(WebGLCommand::StencilMaskSeparate(face, mask)))
+                    .unwrap(),
+            _ => return self.webgl_error(InvalidEnum),
+        }
+    }
+
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.3
+    fn StencilOp(&self, fail: u32, zfail: u32, zpass: u32) {
+        if self.validate_stencil_actions(fail) && self.validate_stencil_actions(zfail) &&
+           self.validate_stencil_actions(zpass) {
+                self.ipc_renderer
+                    .send(CanvasMsg::WebGL(WebGLCommand::StencilOp(fail, zfail, zpass)))
+                    .unwrap()
+        } else {
+            self.webgl_error(InvalidEnum)
+        }
+    }
+
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.3
+    fn StencilOpSeparate(&self, face: u32, fail: u32, zfail: u32, zpass: u32) {
+        match face {
+            constants::FRONT | constants::BACK | constants::FRONT_AND_BACK => (),
+            _ => return self.webgl_error(InvalidEnum),
+        }
+
+        if self.validate_stencil_actions(fail) && self.validate_stencil_actions(zfail) &&
+           self.validate_stencil_actions(zpass) {
+                self.ipc_renderer
+                    .send(CanvasMsg::WebGL(WebGLCommand::StencilOpSeparate(face, fail, zfail, zpass)))
+                    .unwrap()
+        } else {
+            self.webgl_error(InvalidEnum)
+        }
+    }
+
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.9
     fn LinkProgram(&self, program: Option<&WebGLProgram>) {
         if let Some(program) = program {
diff --git a/components/script/dom/webidls/WebGLRenderingContext.webidl b/components/script/dom/webidls/WebGLRenderingContext.webidl
index 97cd853417f..4b29660b190 100644
--- a/components/script/dom/webidls/WebGLRenderingContext.webidl
+++ b/components/script/dom/webidls/WebGLRenderingContext.webidl
@@ -622,12 +622,12 @@ interface WebGLRenderingContextBase
 
     void shaderSource(WebGLShader? shader, DOMString source);
 
-    //void stencilFunc(GLenum func, GLint ref, GLuint mask);
-    //void stencilFuncSeparate(GLenum face, GLenum func, GLint ref, GLuint mask);
-    //void stencilMask(GLuint mask);
-    //void stencilMaskSeparate(GLenum face, GLuint mask);
-    //void stencilOp(GLenum fail, GLenum zfail, GLenum zpass);
-    //void stencilOpSeparate(GLenum face, GLenum fail, GLenum zfail, GLenum zpass);
+    void stencilFunc(GLenum func, GLint ref, GLuint mask);
+    void stencilFuncSeparate(GLenum face, GLenum func, GLint ref, GLuint mask);
+    void stencilMask(GLuint mask);
+    void stencilMaskSeparate(GLenum face, GLuint mask);
+    void stencilOp(GLenum fail, GLenum zfail, GLenum zpass);
+    void stencilOpSeparate(GLenum face, GLenum fail, GLenum zfail, GLenum zpass);
 
     //void texImage2D(GLenum target, GLint level, GLenum internalformat,
     //                GLsizei width, GLsizei height, GLint border, GLenum format,