use arrays, not objects, to track variable declarations

src/Bundle.js

@@ -295,7 +295,7 @@ export default class Bundle {
 		let getterExports = [];
 
 		this.orderedModules.forEach( module => {
-			keys( module.varDeclarations ).forEach( name => {
+			module.varDeclarations.forEach( name => {
 				varDeclarations[ module.replacements[ name ] || name ] = true;
 			});
 		});

src/Module.js

@@ -64,8 +64,9 @@ export default class Module {
 
 		this.replacements = blank();
 
+		this.varDeclarations = [];
+
 		this.definitions = blank();
-		this.varDeclarations = blank();
 		this.definitionPromises = blank();
 		this.modifications = blank();
 
@@ -201,8 +202,8 @@ export default class Module {
 				this.definitions[ name ] = statement;
 			});
 
-			keys( statement.declaresVar ).forEach( name => {
-				this.varDeclarations[ name ] = statement;
+			statement.scope.varDeclarations.forEach( name => {
+				this.varDeclarations.push( name );
 			});
 
 			keys( statement.modifies ).forEach( name => {

src/Statement.js

@@ -18,7 +18,6 @@ export default class Statement {
 
 		this.scope = new Scope();
 		this.defines = blank();
-		this.declaresVar = blank();
 		this.modifies = blank();
 		this.dependsOn = blank();
 		this.stronglyDependsOn = blank();
@@ -143,10 +142,6 @@ export default class Statement {
 		keys( scope.declarations ).forEach( name => {
 			this.defines[ name ] = true;
 		});
-
-		keys( scope.varDeclarations ).forEach( name => {
-			this.declaresVar[ name ] = true;
-		});
 	}
 
 	checkForReads ( scope, node, parent, strong ) {

src/ast/Scope.js

@@ -12,9 +12,10 @@ export default class Scope {
 		this.parent = options.parent;
 		this.depth = this.parent ? this.parent.depth + 1 : 0;
 		this.declarations = blank();
-		this.varDeclarations = blank();
 		this.isBlockScope = !!options.block;
 
+		this.varDeclarations = [];
+
 		if ( options.params ) {
 			options.params.forEach( param => {
 				this.declarations[ param.name ] = param;
@@ -31,7 +32,7 @@ export default class Scope {
 			this.parent.addDeclaration( name, declaration, isVar );
 		} else {
 			this.declarations[ name ] = declaration;
-			if ( isVar ) this.varDeclarations[ name ] = true;
+			if ( isVar ) this.varDeclarations.push( name )
 		}
 	}