Support string literal keys for object expressions

For ObjectExpression, we now support computed keys where the key is a string 
literal.

compiler/forget/src/HIR/BuildHIR.ts

@@ -809,7 +809,12 @@ function lowerExpression(
           continue;
         }
         const key = propertyPath.node.key;
-        if (key.type !== "Identifier") {
+        let keyName: string;
+        if (key.type === "Identifier") {
+          keyName = key.name;
+        } else if (key.type === "StringLiteral") {
+          keyName = key.value;
+        } else {
           builder.errors.push({
             reason: `(BuildHIR::lowerExpression) Expected Identifier, got ${key.type} key in ObjectExpression`,
             severity: ErrorSeverity.InvalidInput,
@@ -827,7 +832,7 @@ function lowerExpression(
           continue;
         }
         const value = lowerExpressionToTemporary(builder, valuePath);
-        properties.set(key.name, value);
+        properties.set(keyName, value);
       }
       return {
         kind: "ObjectExpression",

compiler/forget/src/__tests__/fixtures/hir/object-expression-string-literal-key.expect.md

@@ -0,0 +1,31 @@
+
+## Input
+
+```javascript
+function Component(props) {
+  const x = { ["foo"]: props.foo };
+  return x;
+}
+
+```
+
+## Code
+
+```javascript
+function Component(props) {
+  const $ = React.unstable_useMemoCache(2);
+  const c_0 = $[0] !== props.foo;
+  let t0;
+  if (c_0) {
+    t0 = { foo: props.foo };
+    $[0] = props.foo;
+    $[1] = t0;
+  } else {
+    t0 = $[1];
+  }
+  const x = t0;
+  return x;
+}
+
+```
+      

compiler/forget/src/__tests__/fixtures/hir/object-expression-string-literal-key.js

@@ -0,0 +1,4 @@
+function Component(props) {
+  const x = { ["foo"]: props.foo };
+  return x;
+}