Recognize jsxImportSource namespaces in checked JavaScript (#4694)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: jakebailey <5341706+jakebailey@users.noreply.github.com>

Author: Copilot

internal/compiler/fileloader.go

@@ -547,7 +547,7 @@ func (p *fileLoader) resolveImportsAndModuleAugmentations(t *parseTask) {
 		}
 	}
 
-	if file.ScriptKind == core.ScriptKindJSX || file.ScriptKind == core.ScriptKindTSX {
+	if isJavaScriptFile || file.ScriptKind == core.ScriptKindTSX {
 		jsxImport := ast.GetJSXRuntimeImport(ast.GetJSXImplicitImportBase(optionsForFile, file), optionsForFile)
 		if jsxImport != "" {
 			specifier := p.createSyntheticImport(jsxImport, file)

testdata/baselines/reference/compiler/jsxImportSourceCheckJs.symbols

@@ -0,0 +1,21 @@
+//// [tests/cases/compiler/jsxImportSourceCheckJs.ts] ////
+
+=== /node_modules/preact/jsx-runtime/index.d.ts ===
+export namespace JSX {
+>JSX : Symbol(JSX, Decl(index.d.ts, 0, 0))
+
+    interface Element {}
+>Element : Symbol(Element, Decl(index.d.ts, 0, 22))
+
+    interface IntrinsicElements {
+>IntrinsicElements : Symbol(IntrinsicElements, Decl(index.d.ts, 1, 24))
+
+        div: {};
+>div : Symbol(IntrinsicElements.div, Decl(index.d.ts, 2, 33))
+    }
+}
+
+=== /index.js ===
+<div />;
+>div : Symbol(JSX.IntrinsicElements.div, Decl(index.d.ts, 2, 33))
+

testdata/baselines/reference/compiler/jsxImportSourceCheckJs.types

@@ -0,0 +1,16 @@
+//// [tests/cases/compiler/jsxImportSourceCheckJs.ts] ////
+
+=== /node_modules/preact/jsx-runtime/index.d.ts ===
+export namespace JSX {
+    interface Element {}
+    interface IntrinsicElements {
+        div: {};
+>div : {}
+    }
+}
+
+=== /index.js ===
+<div />;
+><div /> : import("preact/jsx-runtime").JSX.Element
+>div : any
+

testdata/tests/cases/compiler/jsxImportSourceCheckJs.ts

@@ -0,0 +1,17 @@
+// @allowJs: true
+// @checkJs: true
+// @jsx: react-jsx
+// @jsxImportSource: preact
+// @noEmit: true
+// @strict: true
+
+// @filename: /node_modules/preact/jsx-runtime/index.d.ts
+export namespace JSX {
+    interface Element {}
+    interface IntrinsicElements {
+        div: {};
+    }
+}
+
+// @filename: /index.js
+<div />;