Remove some invariants and deadcode

These are not necessary if we enable type checks. Static or dynamic.

They're distracting my greppability.

Also, some dead code in shallow rendering.

src/browser/ui/ReactDOMComponent.js

@@ -172,7 +172,6 @@ ReactDOMComponent.Mixin = {
    * @return {string} The computed markup.
    */
   mountComponent: function(rootID, transaction, mountDepth, context) {
-    invariant(context !== undefined, "Context is required parameter");
     ReactComponent.Mixin.mountComponent.call(
       this,
       rootID,
@@ -287,7 +286,6 @@ ReactDOMComponent.Mixin = {
   },
 
   receiveComponent: function(nextElement, transaction, context) {
-    invariant(context !== undefined, "Context is required parameter");
     if (nextElement === this._currentElement &&
         nextElement._owner != null) {
       // Since elements are immutable after the owner is rendered,
@@ -316,8 +314,6 @@ ReactDOMComponent.Mixin = {
    * @overridable
    */
   updateComponent: function(transaction, prevElement, nextElement, context) {
-    if(context === undefined) throw new Error("Context required for mounting");
-    if(context === null) throw new Error("Assert: context is not null");
     assertValidProps(this._currentElement.props);
     ReactComponent.Mixin.updateComponent.call(
       this,
@@ -435,7 +431,6 @@ ReactDOMComponent.Mixin = {
    * @param {ReactReconcileTransaction} transaction
    */
   _updateDOMChildren: function(lastProps, transaction, context) {
-    invariant(context !== undefined, "Context is required parameter");
     var nextProps = this._currentElement.props;
 
     var lastContent =

src/core/ReactComponent.js

@@ -108,7 +108,6 @@ var ReactComponent = {
      * @internal
      */
     mountComponent: function(rootID, transaction, mountDepth, context) {
-      invariant(context !== undefined, "Context is required parameter");
       var ref = this._currentElement.ref;
       if (ref != null) {
         var owner = this._currentElement._owner;
@@ -144,7 +143,6 @@ var ReactComponent = {
      * @internal
      */
     updateComponent: function(transaction, prevElement, nextElement, context) {
-      invariant(context !== undefined, "Context is required parameter");
       // If either the owner or a `ref` has changed, make sure the newest owner
       // has stored a reference to `this`, and the previous owner (if different)
       // has forgotten the reference to `this`. We use the element instead

src/core/ReactCompositeComponent.js

@@ -158,7 +158,6 @@ var ReactCompositeComponentMixin = assign({},
    * @internal
    */
   mountComponent: function(rootID, transaction, mountDepth, context) {
-    invariant(context !== undefined, "Context is required parameter");
     ReactComponent.Mixin.mountComponent.call(
       this,
       rootID,
@@ -520,7 +519,6 @@ var ReactCompositeComponentMixin = assign({},
   },
 
   receiveComponent: function(nextElement, transaction, context) {
-    invariant(context !== undefined, "Context is required parameter");
     if (nextElement === this._currentElement &&
         nextElement._owner != null) {
       // Since elements are immutable after the owner is rendered,
@@ -589,8 +587,6 @@ var ReactCompositeComponentMixin = assign({},
    * TODO: Remove this check when owner-context is removed
    */
    _warnIfContextsDiffer: function(ownerBasedContext, parentBasedContext) {
-    invariant(ownerBasedContext !== undefined, "Owner based context is required parameter");
-    invariant(parentBasedContext !== undefined, "Parent based ontext is required parameter");
     var ownerKeys = Object.keys(ownerBasedContext).sort();
     var parentKeys = Object.keys(parentBasedContext).sort();
     if (ownerKeys.length != parentKeys.length || ownerKeys.toString() != parentKeys.toString()) {
@@ -720,8 +716,6 @@ var ReactCompositeComponentMixin = assign({},
     transaction,
     unmaskedContext
   ) {
-    invariant(unmaskedContext !== undefined, "Context required for mounting");
-    invariant(unmaskedContext !== null, "Context must be non-null");
     var inst = this._instance;
 
     var prevProps = inst.props;
@@ -755,7 +749,6 @@ var ReactCompositeComponentMixin = assign({},
    * @internal
    */
   _updateRenderedComponent: function(transaction, context) {
-    invariant(context !== undefined, "Context is required parameter");
     var prevComponentInstance = this._renderedComponent;
     var prevRenderedElement = prevComponentInstance._currentElement;
     var nextRenderedElement = this._renderValidatedComponent();
@@ -968,25 +961,11 @@ var ShallowMixin = assign({},
     var prevComponentInstance = this._renderedComponent;
     var prevRenderedElement = prevComponentInstance._currentElement;
     // Use the without-owner-or-context variant of _rVC below:
-    var nextRenderedElement = this._renderValidatedComponentWithoutOwnerOrContext();
-    if (shouldUpdateReactComponent(prevRenderedElement, nextRenderedElement)) {
-      prevComponentInstance.receiveComponent(
-        nextRenderedElement,
-        transaction
-      );
-    } else {
-      // These two IDs are actually the same! But nothing should rely on that.
-      var thisID = this._rootNodeID;
-      var prevComponentID = prevComponentInstance._rootNodeID;
-      // Don't unmount previous instance since it was never mounted, due to
-      // shallow render.
-      //prevComponentInstance.unmountComponent();
-      this._renderedComponent = nextRenderedElement;
-      // ^ no instantiateReactComponent
-      //
-      // no recursive mountComponent
-      return nextRenderedElement;
-    }
+    var nextRenderedElement =
+      this._renderValidatedComponentWithoutOwnerOrContext();
+    // This is a noop in shallow render
+    shouldUpdateReactComponent(prevRenderedElement, nextRenderedElement);
+    this._renderedComponent = nextRenderedElement;
   }
 
 });

src/core/ReactMultiChild.js

@@ -17,7 +17,6 @@ var ReactMultiChildUpdateTypes = require('ReactMultiChildUpdateTypes');
 
 var flattenChildren = require('flattenChildren');
 var instantiateReactComponent = require('instantiateReactComponent');
-var invariant = require('invariant');
 var shouldUpdateReactComponent = require('shouldUpdateReactComponent');
 
 /**
@@ -180,7 +179,6 @@ var ReactMultiChild = {
      * @internal
      */
     mountChildren: function(nestedChildren, transaction, context) {
-      invariant(context !== undefined, "Context is required parameter");
       var children = flattenChildren(nestedChildren);
       var mountImages = [];
       var index = 0;
@@ -244,7 +242,6 @@ var ReactMultiChild = {
      * @internal
      */
     updateChildren: function(nextNestedChildren, transaction, context) {
-      invariant(context !== undefined, "Context is required parameter");
       updateDepth++;
       var errorThrown = true;
       try {
@@ -268,7 +265,6 @@ var ReactMultiChild = {
      * @protected
      */
     _updateChildren: function(nextNestedChildren, transaction, context) {
-      invariant(context !== undefined, "Context is required parameter");
       var nextChildren = flattenChildren(nextNestedChildren);
       var prevChildren = this._renderedChildren;
       if (!nextChildren && !prevChildren) {
@@ -400,7 +396,6 @@ var ReactMultiChild = {
       index,
       transaction,
       context) {
-      invariant(context !== undefined, "Context is required parameter");
       // Inlined for performance, see `ReactInstanceHandles.createReactID`.
       var rootID = this._rootNodeID + name;
       var mountImage = child.mountComponent(