Redo "Add more MiniJsParser functionality."

sdk/lib/_internal/compiler/implementation/js/nodes.dart

Index: sdk/lib/_internal/compiler/implementation/js/nodes.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js/nodes.dart b/sdk/lib/_internal/compiler/implementation/js/nodes.dart
index 46d421b916f328cb9da10ac9bb06126449ad9b6f..b48c4aeb4ebebc023b14aa3a59a0d2041ab7d0d8 100644
--- a/sdk/lib/_internal/compiler/implementation/js/nodes.dart
+++ b/sdk/lib/_internal/compiler/implementation/js/nodes.dart
@@ -64,6 +64,7 @@ abstract class NodeVisitor<T> {
   T visitComment(Comment node);
 
   T visitInterpolatedExpression(InterpolatedExpression node);
+  T visitInterpolatedStatement(InterpolatedStatement node);
   T visitJSExpression(JSExpression node);
 }
 
@@ -151,6 +152,8 @@ class BaseVisitor<T> implements NodeVisitor<T> {
 
   T visitInterpolatedExpression(InterpolatedExpression node)
       => visitExpression(node);
+  T visitInterpolatedStatement(InterpolatedStatement node)
+      => visitStatement(node);
   T visitJSExpression(JSExpression node) => visitExpression(node);
 
   // Ignore comments by default.
@@ -949,11 +952,18 @@ class Property extends Node {
   }
 }
 
-class InterpolatedExpression extends Expression {
+/// Tag class for all interpolated positions.
+abstract class InterpolatedNode implements Node {}
+
+class InterpolatedExpression extends Expression implements InterpolatedNode {
   Expression value;
 
   InterpolatedExpression(this.value);
 
+  void assign(Expression newValue) {
+    value = newValue;
+  }
+
   accept(NodeVisitor visitor) => visitor.visitInterpolatedExpression(this);
 
   void visitChildren(NodeVisitor visitor) {
@@ -963,24 +973,45 @@ class InterpolatedExpression extends Expression {
   int get precedenceLevel => value.precedenceLevel;
 }
 
+class InterpolatedStatement extends Statement implements InterpolatedNode {
+  Statement value;
+
+  InterpolatedStatement(this.value);
+
+  void assign(Node newValue) {
+    if (newValue is Expression)
+      value = new ExpressionStatement(newValue);
+    else
+      value = newValue;
+  }
+
+  accept(NodeVisitor visitor) => visitor.visitInterpolatedStatement(this);
+
+  void visitChildren(NodeVisitor visitor) {
+    if (value != null) value.accept(visitor);
+  }
+}
+
 class JSExpression extends Expression {
   Expression value;
-  List<InterpolatedExpression> interpolatedExpressions;
+  List<InterpolatedNode> interpolatedNodes;
 
-  JSExpression(this.value, this.interpolatedExpressions);
+  JSExpression(this.value, this.interpolatedNodes);
 
   accept(NodeVisitor visitor) => visitor.visitJSExpression(this);
 
   void visitChildren(NodeVisitor visitor) {
     value.accept(visitor);
-    for (InterpolatedExpression expression in interpolatedExpressions) {
-      expression.accept(visitor);
+    for (InterpolatedNode node in interpolatedNodes) {
+      node.accept(visitor);
     }
   }
 
   int get precedenceLevel => value.precedenceLevel;
 }
 
+// TODO(sra): JSStatement like JSExpression.
+
 /**
  * [RegExpLiteral]s, despite being called "Literal", do not inherit from
  * [Literal]. Indeed, regular expressions in JavaScript have a side-effect and